Subject: Re: [Fot] Camshaft recommendation

From: Richard Good via Fot <[email-masked]>
Date: Wed, 12 Feb 2020 16:25:10 +0000 (UTC)

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Marcel,

Yes, if you increase rocker ratio and do not change the cam lift, the maxim=
um lift will also increase by 13%.

Richard

Sent from AOL Mobile Mail=20
Get the new AOL app: mail.mobile.aol.com
On Wednesday, February 12, 2020 van.mulders.marcel <van.mulders.marcel@tele=
net.be> wrote:
Richard,=C2=A0dare I answer this...Do you mean that, with the higher rocker=
 ratio, the valve is moving faster in the first part of the opening phase a=
nd hence moving slower nearing the maximum lift? Suppose the cam lift of bo=
th camshafts is such that the maximum lift is 13mm for both the 1.65 and 1.=
50 ratio and duration at 0.050" is 240=C2=B0, thus the crank has to move 12=
0=C2=B0 to go from 0.050" lift to maximum lift in both cases. If the valve =
is opening 13% faster all the way from 0.050" lift untill maximum lift, the=
 maximum lift will also be 13% higher! When an engine is at, say 5000rpm or=
 any other speed, it takes the same time to move 120=C2=B0 (from 0.050" to =
maximum lift) : the rocker arm ratio does not change that and the valve tha=
t is opening 13% faster with the 1.65 ratio will end at a maximum lift that=
 is also 13% higher.=C2=A0MarcelVan: "Richard Good" <[email-masked]>=
)
Aan: "Michael Zbarsky" <[email-masked]>, [email-masked], "van =
mulders marcel" <[email-masked]>
Cc: "fot" <[email-masked]>
Verzonden: Woensdag 12 februari 2020 02:23:07
Onderwerp: Re: [Fot] Camshaft recommendation
=C2=A07.887
Michael,

People often seem to overlook the main performance benefit of increasing th=
e rocker ratio.=C2=A0 That is the increase in valve velocity.=C2=A0 The vel=
ocity of a flat tappet is limited by it's diameter. If you grind the cam lo=
be for too much velocity the contact patch will move out past the edge of t=
he lifter and things will self destruct.=C2=A0 So tappet velocity is limite=
d.=C2=A0 However, since tappet velocity times rocker ratio equals valve vel=
ocity, increasing the rocker ratio will increase valve velocity.

First decide what will be the optimum valve lift for your engine then divid=
e by rocker ratio to determine the net cam lift needed to achieve that valv=
e lift.=C2=A0 Yes, you can grind the cam with a large enough lobe to reach =
desired lift using stock rockers but you are limited in how fast you can op=
en the valve.=C2=A0 Now if you grind the cam with less lift then use 1.65:1=
 rockers to reach that same desired valve lift you will be moving the valve=
 about 13% faster. That means it will be open further in a given period of =
time.=C2=A0 Graph it out and you will see a big difference.=C2=A0 Valve vel=
ocity is a huge factor in performance.=C2=A0=20

I can understand why someone who has tried to use high ratio rockers with a=
 cam that was already maxing out the valve lift with stock rockers would de=
cide that high ratio does not work.=C2=A0 Valve lift was already at max. In=
creasing it further may be a detriment.=C2=A0 If duration was also maxed ou=
t for reasonable torque then the increase in lift during the overlap period=
 caused by the increase in rocker ratio may reduce the low end torque.=C2=
=A0 Properly applied with the right cam profile, high ratio rockers enable =
performance that is just not achievable with stock rockers.

Richard Good
Good Parts Inc

Sent from AOL Mobile Mail=20
Get the new AOL app: mail.mobile.aol.com
On Tuesday, February 11, 2020 Michael Zbarsky via Fot <[email-masked]> =
wrote:
Thanks everyone! Good stuff. I=E2=80=99m sticking to a redline of just over=
=C2=A06K. I=E2=80=99d also like to keep the 1.65 setup rather than invest i=
n a 1.55 so keep the intel and=C2=A0suggestions coming. The GP3 is a defini=
te contender.=C2=A0
Mike=C2=A0

On Monday, February 10, 2020, 4:07 PM, Geoff Byrne <[email-masked]=
> wrote:

Ditch the 1.65 rockers no good for racingGeoff ByrneTR6 racer down under

Sent from my iPhone

On 11 Feb 2020, at 12:52 am, van.mulders.marcel--- via Fot <[email-masked].=
net> wrote:

I also once bought a Goodparts 1.65 rocker roller assembly for a TR6 engine=
, but in the end I had to use a 1.55 roller rocker assembly, also from Good=
parts, because, with the 1.65, it is difficult to find a race camshaft with=
 a=C2=A0 lobe lift that is low enough. With lobes of 8mm or higher, I could=
 not find valve springs to cope with the high valve lift. I bought a G5 cam=
shaft from Schneider, they call it=C2=A0 the 320-F grind (duration is 268=
=C2=B0 at 0.050", timing is 57-83=C2=A0 =C2=A0 87-53 , installation figure =
is then 103=C2=B0 :is that the same as the G5 grind?) with 0.340"/8.6mm cam=
 lift and that makes for a=C2=A0 valve lift of 12.9mm with the 1.55 rocker =
arms. With 1.65 rockers , valve lift would be 14.2mm and I could not find v=
alve springs for that lift. The valve springs I used are part no 281003-063=
.20 from Summit (Isky), 320lb/inch spring rate. They recommend 0.45"/11.43m=
m=C2=A0 (1.250" - 0.800"from closed to full open position, so it is about 1=
.4mm more in my engine, but there is no problem concerning=C2=A0 coil bindi=
ng : the installed height is a 1mm more than 1.250 , the pressure in closed=
 position is lower=C2=A0 of course, but still 34kgs (105kgs at full lift) a=
n that seems to be enough till 7500 rpmRacetorations have a race cam with 7=
.6mm cam lift, probably that would work with 1.65 rocker arms. I still have=
 the 1.65 rocker assembly, it is new and it could work with a road cam or a=
ny camshaft with a maximum of 8mm cam lift.Marcel
Van: "fot" <[email-masked]>
Aan: "fot" <[email-masked]>
Verzonden: Maandag 10 februari 2020 02:34:27
Onderwerp: [Fot] Camshaft recommendation

Hi all, I=E2=80=99m building a TR6 race engine and have a set of 1.65 ratio=
 roller rockers from Goodparts. Any recommendations for a suitable camshaft=
? I will be putting in cam bearings.=C2=A0
Thanks, Mike

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home.com.au

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izon.net

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<p dir=3D"ltr">Marcel,</p>
<p dir=3D"ltr">Yes, if you increase rocker ratio and do not change the cam =
lift, the maximum lift will also increase by 13%.</p>
<p dir=3D"ltr">Richard</p>
<p dir=3D"ltr">Sent from AOL Mobile Mail <br>
Get the new AOL app: mail.mobile.aol.com</p>
</br></br><div class=3D"device_aol_et_org_dt_dd_quote"></div><hr style=3D"b=
order:0;height:1px;color:#999;background-color:#999;width:100%;margin:0 0 9=
px 0;padding:0;"></hr><span style=3D"font-size:14px; color:#999999;">On Wed=
nesday, February 12, 2020 van.mulders.marcel &#60;<span style=3D"color:#000=
0A0">[email-masked]</span>&#62; wrote:</span><br></br><div i=
d=3D"yiv9741220511"><html><div><div style=3D"font-family:Verdana, Arial, He=
lvetica, sans-serif;font-size:10pt;color:#000000;"><div>Richard,=C2=A0</div=
><div>dare I answer this...</div><div>Do you mean that, with the higher roc=
ker ratio, the valve is moving faster in the first part of the opening phas=
e and hence moving slower nearing the maximum lift? Suppose the cam lift of=
 both camshafts is such that the maximum lift is 13mm for both the 1.65 and=
 1.50 ratio and duration at 0.050&quot; is 240=C2=B0, thus the crank has to=
 move 120=C2=B0 to go from 0.050&quot; lift to maximum lift in both cases. =
If the valve is opening 13% faster all the way from 0.050&quot; lift untill=
 maximum lift, the maximum lift will also be 13% higher! When an engine is =
at, say 5000rpm or any other speed, it takes the same time to move 120=C2=
=B0 (from 0.050&quot; to maximum lift) : the rocker arm ratio does not chan=
ge that and the valve that is opening 13% faster with the 1.65 ratio will e=
nd at a maximum lift that is also 13% higher.=C2=A0</div><div>Marcel</div><=
hr id=3D"yiv9741220511zwchr"><div><b>Van: </b>&quot;Richard Good&quot; &lt;=
[email-masked]&gt;)<br clear=3D"none"><b>Aan: </b>&quot;Michael Zbar=
sky&quot; &lt;[email-masked]&gt;, [email-masked], &quot;van mu=
lders marcel&quot; &lt;[email-masked]&gt;<div class=3D"yiv97=
41220511yqt0090589858" id=3D"yiv9741220511yqtfd74605"><br clear=3D"none"><b=
>Cc: </b>&quot;fot&quot; &lt;[email-masked]&gt;<br clear=3D"none"><b>Ve=
rzonden: </b>Woensdag 12 februari 2020 02:23:07<br clear=3D"none"><b>Onderw=
erp: </b>Re: [Fot] Camshaft recommendation<br clear=3D"none"></div></div><d=
iv class=3D"yiv9741220511yqt0090589858" id=3D"yiv9741220511yqtfd30775"><div=
>=C2=A07.887</div><div><p dir=3D"ltr">Michael,</p>
<p dir=3D"ltr">People often seem to overlook the main performance benefit o=
f increasing the rocker ratio.=C2=A0 That is the increase in valve velocity=
.=C2=A0 The velocity of a flat tappet is limited by it&#39;s diameter. If y=
ou grind the cam lobe for too much velocity the contact patch will move out=
 past the edge of the lifter and things will self destruct.=C2=A0 So tappet=
 velocity is limited.=C2=A0 However, since tappet velocity times rocker rat=
io equals valve velocity, increasing the rocker ratio will increase valve v=
elocity.</p>
<p dir=3D"ltr">First decide what will be the optimum valve lift for your en=
gine then divide by rocker ratio to determine the net cam lift needed to ac=
hieve that valve lift.=C2=A0 Yes, you can grind the cam with a large enough=
 lobe to reach desired lift using stock rockers but you are limited in how =
fast you can open the valve.=C2=A0 Now if you grind the cam with less lift =
then use 1.65:1 rockers to reach that same desired valve lift you will be m=
oving the valve about 13% faster. That means it will be open further in a g=
iven period of time.=C2=A0 Graph it out and you will see a big difference.=
=C2=A0 Valve velocity is a huge factor in performance.=C2=A0 </p>
<p dir=3D"ltr">I can understand why someone who has tried to use high ratio=
 rockers with a cam that was already maxing out the valve lift with stock r=
ockers would decide that high ratio does not work.=C2=A0 Valve lift was alr=
eady at max. Increasing it further may be a detriment.=C2=A0 If duration wa=
s also maxed out for reasonable torque then the increase in lift during the=
 overlap period caused by the increase in rocker ratio may reduce the low e=
nd torque.=C2=A0 Properly applied with the right cam profile, high ratio ro=
ckers enable performance that is just not achievable with stock rockers.</p=
<p dir=3D"ltr">Richard Good<br clear=3D"none">
Good Parts Inc</p>
<p dir=3D"ltr">Sent from AOL Mobile Mail <br clear=3D"none">
Get the new AOL app: mail.mobile.aol.com</p>
<div class=3D"yiv9741220511device_aol_et_org_dt_dd_quote"></div><hr style=
=3D"border:0;min-height:1px;color:#999;background-color:#999;width:100%;mar=
gin:0 0 9px 0;padding:0;"><span style=3D"font-size:14px;color:#999999;">On =
Tuesday, February 11, 2020 Michael Zbarsky via Fot &lt;<span style=3D"color=
:#0000a0;">[email-masked]</span>&gt; wrote:</span><br clear=3D"none"><d=
iv id=3D"yiv9741220511"></div><div>
Thanks everyone! Good stuff. I=E2=80=99m sticking to a redline of just over=
=C2=A06K. I=E2=80=99d also like to keep the 1.65 setup rather than invest i=
n a 1.55 so keep the intel and=C2=A0suggestions coming. The GP3 is a defini=
te contender.=C2=A0<div><br clear=3D"none"></div><div>Mike=C2=A0<br clear=
=3D"none"><br clear=3D"none"><br clear=3D"none"><br clear=3D"none"><div cla=
ss=3D"yiv9741220511yqt2182859488" id=3D"yiv9741220511yqt21880"><p class=3D"=
yiv9741220511yahoo-quoted-begin" style=3D"font-size:15px;color:#715ffa;padd=
ing-top:15px;margin-top:0;">On Monday, February 10, 2020, 4:07 PM, Geoff By=
rne &lt;[email-masked]&gt; wrote:</p><blockquote class=3D"yiv97412=
20511iosymail"><div id=3D"yiv9741220511"><div>Ditch the 1.65 rockers no goo=
d for racing<div>Geoff Byrne</div><div>TR6 racer down under<br clear=3D"non=
e"><br clear=3D"none"><div dir=3D"ltr">Sent from my iPhone</div><div dir=3D=
"ltr"><br clear=3D"none"><blockquote>On 11 Feb 2020, at 12:52 am, van.mulde=
rs.marcel--- via Fot &lt;[email-masked]&gt; wrote:<br clear=3D"none"><b=
r clear=3D"none"></blockquote></div><blockquote><div dir=3D"ltr"><div style=
=3D"font-family:'verdana' , 'arial' , 'helvetica' , sans-serif;font-size:10=
pt;color:#000000;"><div>I also once bought a Goodparts 1.65 rocker roller a=
ssembly for a TR6 engine, but in the end I had to use a 1.55 roller rocker =
assembly, also from Goodparts, because, with the 1.65, it is difficult to f=
ind a race camshaft with a=C2=A0 lobe lift that is low enough. With lobes o=
f 8mm or higher, I could not find valve springs to cope with the high valve=
 lift. I bought a G5 camshaft from Schneider, they call it=C2=A0 the 320-F =
grind (duration is 268=C2=B0 at 0.050&quot;, timing is 57-83=C2=A0 =C2=A0 8=
7-53 , installation figure is then 103=C2=B0 :is that the same as the G5 gr=
ind?) with 0.340&quot;/8.6mm cam lift and that makes for a=C2=A0 valve lift=
 of 12.9mm with the 1.55 rocker arms. With 1.65 rockers , valve lift would =
be 14.2mm and I could not find valve springs for that lift. The valve sprin=
gs I used are part no 281003-063.20 from Summit (Isky), 320lb/inch spring r=
ate. They recommend 0.45&quot;/11.43mm=C2=A0 (1.250&quot; - 0.800&quot;from=
 closed to full open position, so it is about 1.4mm more in my engine, but =
there is no problem concerning=C2=A0 coil binding : the installed height is=
 a 1mm more than 1.250 , the pressure in closed position is lower=C2=A0 of =
course, but still 34kgs (105kgs at full lift) an that seems to be enough ti=
ll 7500 rpm</div><div>Racetorations have a race cam with 7.6mm cam lift, pr=
obably that would work with 1.65 rocker arms. I still have the 1.65 rocker =
assembly, it is new and it could work with a road cam or any camshaft with =
a maximum of 8mm cam lift.</div><div>Marcel</div><div><br clear=3D"none"></=
div><hr id=3D"yiv9741220511zwchr"><div><b>Van: </b>&quot;fot&quot; &lt;fot@=
autox.team.net&gt;<br clear=3D"none"><b>Aan: </b>&quot;fot&quot; &lt;fot@au=
tox.team.net&gt;<br clear=3D"none"><b>Verzonden: </b>Maandag 10 februari 20=
20 02:34:27<br clear=3D"none"><b>Onderwerp: </b>[Fot] Camshaft recommendati=
on<br clear=3D"none"></div><div><br clear=3D"none"></div><div>
Hi all, I=E2=80=99m building a TR6 race engine and have a set of 1.65 ratio=
 roller rockers from Goodparts. Any recommendations for a suitable camshaft=
? I will be putting in cam bearings.=C2=A0<div><br clear=3D"none"><div>Than=
ks, Mike<br clear=3D"none"><br clear=3D"none"><br clear=3D"none"></div></di=
v>
<br clear=3D"none">_______________________________________________<br clear=
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_______________________________________________
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--===============3550129795550633399==--

---

From: "van.mulders.marcel--- via Fot" <[email-masked]>
Date: Wed, 12 Feb 2020 19:19:58 +0100 (CET)

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Richard,=20
dare I answer again...=20
You say :" first decide what will be the optimum lift for your engine , the=
n... ": in that case : what is the point of high ratio rocker arms, if you =
want to end at the same maximum valve lift? With a higher lobe x lower rock=
er ratio, the valve opening speed will be the same and you have a lower for=
ce (load) at the pushrods and lobe/cam followers. I think the only reason f=
or a higher rocker ratio is the camfollowers having a too small a diameter =
to be able to get at the maximum valve lift you want?=20
Marcel=20

Van: "Richard Good" <[email-masked]>=20
Aan: "van mulders marcel" <[email-masked]>=20
Cc: "fot" <[email-masked]>=20
Verzonden: Woensdag 12 februari 2020 17:25:10=20
Onderwerp: Re: [Fot] Camshaft recommendation=20

Marcel,=20

Yes, if you increase rocker ratio and do not change the cam lift, the maxim=
um lift will also increase by 13%.=20

Richard=20

Sent from AOL Mobile Mail=20
Get the new AOL app: mail.mobile.aol.com=20

On Wednesday, February 12, 2020 van.mulders.marcel < van.mulders.marcel@tel=
enet.be > wrote:=20
Richard,=20
dare I answer this...=20
Do you mean that, with the higher rocker ratio, the valve is moving faster =
in the first part of the opening phase and hence moving slower nearing the =
maximum lift? Suppose the cam lift of both camshafts is such that the maxim=
um lift is 13mm for both the 1.65 and 1.50 ratio and duration at 0.050" is =
240=C2=B0, thus the crank has to move 120=C2=B0 to go from 0.050" lift to m=
aximum lift in both cases. If the valve is opening 13% faster all the way f=
rom 0.050" lift untill maximum lift, the maximum lift will also be 13% high=
er! When an engine is at, say 5000rpm or any other speed, it takes the same=
 time to move 120=C2=B0 (from 0.050" to maximum lift) : the rocker arm rati=
o does not change that and the valve that is opening 13% faster with the 1.=
65 ratio will end at a maximum lift that is also 13% higher.=20
Marcel=20

Van: "Richard Good" <[email-masked]>)=20
Aan: "Michael Zbarsky" <[email-masked]>, [email-masked], "van =
mulders marcel" <[email-masked]>=20

Cc: "fot" <[email-masked]>=20
Verzonden: Woensdag 12 februari 2020 02:23:07=20
Onderwerp: Re: [Fot] Camshaft recommendation=20
7.887=20

Michael,=20

People often seem to overlook the main performance benefit of increasing th=
e rocker ratio. That is the increase in valve velocity. The velocity of a f=
lat tappet is limited by it's diameter. If you grind the cam lobe for too m=
uch velocity the contact patch will move out past the edge of the lifter an=
d things will self destruct. So tappet velocity is limited. However, since =
tappet velocity times rocker ratio equals valve velocity, increasing the ro=
cker ratio will increase valve velocity.=20

First decide what will be the optimum valve lift for your engine then divid=
e by rocker ratio to determine the net cam lift needed to achieve that valv=
e lift. Yes, you can grind the cam with a large enough lobe to reach desire=
d lift using stock rockers but you are limited in how fast you can open the=
 valve. Now if you grind the cam with less lift then use 1.65:1 rockers to =
reach that same desired valve lift you will be moving the valve about 13% f=
aster. That means it will be open further in a given period of time. Graph =
it out and you will see a big difference. Valve velocity is a huge factor i=
n performance.=20

I can understand why someone who has tried to use high ratio rockers with a=
 cam that was already maxing out the valve lift with stock rockers would de=
cide that high ratio does not work. Valve lift was already at max. Increasi=
ng it further may be a detriment. If duration was also maxed out for reason=
able torque then the increase in lift during the overlap period caused by t=
he increase in rocker ratio may reduce the low end torque. Properly applied=
 with the right cam profile, high ratio rockers enable performance that is =
just not achievable with stock rockers.=20

Richard Good=20
Good Parts Inc=20

Sent from AOL Mobile Mail=20
Get the new AOL app: mail.mobile.aol.com=20

On Tuesday, February 11, 2020 Michael Zbarsky via Fot < [email-masked] =
> wrote:=20
Thanks everyone! Good stuff. I=E2=80=99m sticking to a redline of just over=
 6K. I=E2=80=99d also like to keep the 1.65 setup rather than invest in a 1=
.55 so keep the intel and suggestions coming. The GP3 is a definite contend=
er.=20

Mike=20

> wrote:=20

Ditch the 1.65 rockers no good for racing=20
Geoff Byrne=20
TR6 racer down under=20

Sent from my iPhone=20

BQ_BEGIN
net> wrote:=20

BQ_BEGIN

I also once bought a Goodparts 1.65 rocker roller assembly for a TR6 engine=
, but in the end I had to use a 1.55 roller rocker assembly, also from Good=
parts, because, with the 1.65, it is difficult to find a race camshaft with=
 a lobe lift that is low enough. With lobes of 8mm or higher, I could not f=
ind valve springs to cope with the high valve lift. I bought a G5 camshaft =
from Schneider, they call it the 320-F grind (duration is 268=C2=B0 at 0.05=
0", timing is 57-83 87-53 , installation figure is then 103=C2=B0 :is that =
the same as the G5 grind?) with 0.340"/8.6mm cam lift and that makes for a =
valve lift of 12.9mm with the 1.55 rocker arms. With 1.65 rockers , valve l=
ift would be 14.2mm and I could not find valve springs for that lift. The v=
alve springs I used are part no 281003-063.20 from Summit (Isky), 320lb/inc=
h spring rate. They recommend 0.45"/11.43mm (1.250" - 0.800"from closed to =
full open position, so it is about 1.4mm more in my engine, but there is no=
 problem concerning coil binding : the installed height is a 1mm more than =
1.250 , the pressure in closed position is lower of course, but still 34kgs=
 (105kgs at full lift) an that seems to be enough till 7500 rpm=20
Racetorations have a race cam with 7.6mm cam lift, probably that would work=
 with 1.65 rocker arms. I still have the 1.65 rocker assembly, it is new an=
d it could work with a road cam or any camshaft with a maximum of 8mm cam l=
ift.=20
Marcel=20

Van: "fot" <[email-masked]>=20
Aan: "fot" <[email-masked]>=20
Verzonden: Maandag 10 februari 2020 02:34:27=20
Onderwerp: [Fot] Camshaft recommendation=20

Hi all, I=E2=80=99m building a TR6 race engine and have a set of 1.65 ratio=
 roller rockers from Goodparts. Any recommendations for a suitable camshaft=
? I will be putting in cam bearings.=20

Thanks, Mike=20

_______________________________________________=20
[email-masked]=20

http://www.fot-racing.com=20

Archive: http://autox.team.net/archive http://www.team.net/pipermail/fot=20
[email-masked]=20

_______________________________________________=20
[email-masked]=20

http://www.fot-racing.com=20

Archive: http://autox.team.net/archive http://www.team.net/pipermail/fot=20

home.com.au=20

BQ_END

BQ_BEGIN

BQ_END

BQ_END

_______________________________________________=20
[ mailto:[email-masked] | [email-masked] ]=20

[ http://www.fot-racing.com/ | http://www.fot-racing.com ]=20

 ]=20
Archive: [ http://autox.team.net/archive | http://autox.team.net/archive  ]=
 [ http://www.team.net/pipermail/fot | http://www.team.net/pipermail/fot ]=
=20
erizon.net | http://autox.team.net/mailman/options/fot/[email-masked]=
t ]=20

--=_5ce9d9df-ceb4-4bb4-8229-5408bf0e06db
Content-Transfer-Encoding: quoted-printable

<html><body><div style=3D"font-family: Verdana, Arial, Helvetica, sans-seri=
f; font-size: 10pt; color: #000000"><div><br></div><div>Richard,</div><div>=
dare I answer again...</div><div>You say :" first decide what will be the o=
ptimum lift for your engine , then... ": in that case : what is the point o=
f high ratio rocker arms, if you want to end at the same maximum valve lift=
? With a higher lobe x lower rocker ratio, the valve opening speed will be =
the same and you have a lower force (load) at the pushrods and lobe/cam fol=
lowers. I think the only reason for a higher rocker ratio is the camfollowe=
rs having a too small a diameter to be able to get at the maximum valve lif=
t you want?</div><div>Marcel</div><hr id=3D"zwchr" data-marker=3D"__DIVIDER=
__"><div data-marker=3D"__HEADERS__"><b>Van: </b>"Richard Good" &lt;goodpar=
[email-masked]&gt;<br><b>Aan: </b>"van mulders marcel" &lt;van.mulders.marc=
[email-masked]&gt;<br><b>Cc: </b>"fot" &lt;[email-masked]&gt;<br><b>Verz=
onden: </b>Woensdag 12 februari 2020 17:25:10<br><b>Onderwerp: </b>Re: [Fot=
] Camshaft recommendation<br></div><div><br></div><div data-marker=3D"__QUO=
TED_TEXT__"><p dir=3D"ltr">Marcel,</p>
<p dir=3D"ltr">Yes, if you increase rocker ratio and do not change the cam =
lift, the maximum lift will also increase by 13%.</p>
<p dir=3D"ltr">Richard</p>
<p dir=3D"ltr">Sent from AOL Mobile Mail <br>
Get the new AOL app: mail.mobile.aol.com</p>
<div class=3D"device_aol_et_org_dt_dd_quote"></div><hr style=3D"border:0;he=
ight:1px;color:#999;background-color:#999;width:100%;margin:0 0 9px 0;paddi=
ng:0"><span style=3D"font-size:14px;color:#999999">On Wednesday, February 1=
2, 2020 van.mulders.marcel &lt;<span style=3D"color:#0000a0">van.mulders.ma=
[email-masked]</span>&gt; wrote:</span><br><div id=3D"yiv9741220511"></div=
><div><div style=3D"font-family:'verdana' , 'arial' , 'helvetica' , sans-se=
rif;font-size:10pt;color:#000000"><div>Richard,&nbsp;</div><div>dare I answ=
er this...</div><div>Do you mean that, with the higher rocker ratio, the va=
lve is moving faster in the first part of the opening phase and hence movin=
g slower nearing the maximum lift? Suppose the cam lift of both camshafts i=
s such that the maximum lift is 13mm for both the 1.65 and 1.50 ratio and d=
uration at 0.050" is 240=C2=B0, thus the crank has to move 120=C2=B0 to go =
from 0.050" lift to maximum lift in both cases. If the valve is opening 13%=
 faster all the way from 0.050" lift untill maximum lift, the maximum lift =
will also be 13% higher! When an engine is at, say 5000rpm or any other spe=
ed, it takes the same time to move 120=C2=B0 (from 0.050" to maximum lift) =
: the rocker arm ratio does not change that and the valve that is opening 1=
3% faster with the 1.65 ratio will end at a maximum lift that is also 13% h=
igher.&nbsp;</div><div>Marcel</div><hr id=3D"yiv9741220511zwchr"><div><b>Va=
n: </b>"Richard Good" &lt;[email-masked]&gt;)<br clear=3D"none"><b>A=
an: </b>"Michael Zbarsky" &lt;[email-masked]&gt;, [email-masked].=
au, "van mulders marcel" &lt;[email-masked]&gt;<div class=3D=
"yiv9741220511yqt0090589858" id=3D"yiv9741220511yqtfd74605"><br clear=3D"no=
ne"><b>Cc: </b>"fot" &lt;[email-masked]&gt;<br clear=3D"none"><b>Verzon=
den: </b>Woensdag 12 februari 2020 02:23:07<br clear=3D"none"><b>Onderwerp:=
 </b>Re: [Fot] Camshaft recommendation<br clear=3D"none"></div></div><div c=
lass=3D"yiv9741220511yqt0090589858" id=3D"yiv9741220511yqtfd30775"><div>&nb=
sp;7.887</div><div><p dir=3D"ltr">Michael,</p>
<p dir=3D"ltr">People often seem to overlook the main performance benefit o=
f increasing the rocker ratio.&nbsp; That is the increase in valve velocity=
.&nbsp; The velocity of a flat tappet is limited by it's diameter. If you g=
rind the cam lobe for too much velocity the contact patch will move out pas=
t the edge of the lifter and things will self destruct.&nbsp; So tappet vel=
ocity is limited.&nbsp; However, since tappet velocity times rocker ratio e=
quals valve velocity, increasing the rocker ratio will increase valve veloc=
ity.</p>
<p dir=3D"ltr">First decide what will be the optimum valve lift for your en=
gine then divide by rocker ratio to determine the net cam lift needed to ac=
hieve that valve lift.&nbsp; Yes, you can grind the cam with a large enough=
 lobe to reach desired lift using stock rockers but you are limited in how =
fast you can open the valve.&nbsp; Now if you grind the cam with less lift =
then use 1.65:1 rockers to reach that same desired valve lift you will be m=
oving the valve about 13% faster. That means it will be open further in a g=
iven period of time.&nbsp; Graph it out and you will see a big difference.&=
nbsp; Valve velocity is a huge factor in performance.&nbsp; </p>
<p dir=3D"ltr">I can understand why someone who has tried to use high ratio=
 rockers with a cam that was already maxing out the valve lift with stock r=
ockers would decide that high ratio does not work.&nbsp; Valve lift was alr=
eady at max. Increasing it further may be a detriment.&nbsp; If duration wa=
s also maxed out for reasonable torque then the increase in lift during the=
 overlap period caused by the increase in rocker ratio may reduce the low e=
nd torque.&nbsp; Properly applied with the right cam profile, high ratio ro=
ckers enable performance that is just not achievable with stock rockers.</p=
<p dir=3D"ltr">Richard Good<br clear=3D"none">
Good Parts Inc</p>
<p dir=3D"ltr">Sent from AOL Mobile Mail <br clear=3D"none">
Get the new AOL app: mail.mobile.aol.com</p>
<div class=3D"yiv9741220511device_aol_et_org_dt_dd_quote"></div><hr style=
=3D"border:0;min-height:1px;color:#999;background-color:#999;width:100%;mar=
gin:0 0 9px 0;padding:0"><span style=3D"font-size:14px;color:#999999">On Tu=
esday, February 11, 2020 Michael Zbarsky via Fot &lt;<span style=3D"color:#=
0000a0">[email-masked]</span>&gt; wrote:</span><br clear=3D"none"><div =
id=3D"yiv9741220511"></div><div>
Thanks everyone! Good stuff. I=E2=80=99m sticking to a redline of just over=
&nbsp;6K. I=E2=80=99d also like to keep the 1.65 setup rather than invest i=
n a 1.55 so keep the intel and&nbsp;suggestions coming. The GP3 is a defini=
te contender.&nbsp;<div><br clear=3D"none"></div><div>Mike&nbsp;<br clear=
=3D"none"><br clear=3D"none"><br clear=3D"none"><br clear=3D"none"><div cla=
ss=3D"yiv9741220511yqt2182859488" id=3D"yiv9741220511yqt21880"><p class=3D"=
yiv9741220511yahoo-quoted-begin" style=3D"font-size:15px;color:#715ffa;padd=
ing-top:15px;margin-top:0">On Monday, February 10, 2020, 4:07 PM, Geoff Byr=
ne &lt;[email-masked]&gt; wrote:</p><blockquote class=3D"yiv974122=
0511iosymail"><div id=3D"yiv9741220511"><div>Ditch the 1.65 rockers no good=
 for racing<div>Geoff Byrne</div><div>TR6 racer down under<br clear=3D"none=
"><br clear=3D"none"><div dir=3D"ltr">Sent from my iPhone</div><div dir=3D"=
ltr"><br clear=3D"none"><blockquote>On 11 Feb 2020, at 12:52 am, van.mulder=
s.marcel--- via Fot &lt;[email-masked]&gt; wrote:<br clear=3D"none"><br=
 clear=3D"none"></blockquote></div><blockquote><div dir=3D"ltr"><div style=
=3D"font-family:'verdana' , 'arial' , 'helvetica' , sans-serif;font-size:10=
pt;color:#000000"><div>I also once bought a Goodparts 1.65 rocker roller as=
sembly for a TR6 engine, but in the end I had to use a 1.55 roller rocker a=
ssembly, also from Goodparts, because, with the 1.65, it is difficult to fi=
nd a race camshaft with a&nbsp; lobe lift that is low enough. With lobes of=
 8mm or higher, I could not find valve springs to cope with the high valve =
lift. I bought a G5 camshaft from Schneider, they call it&nbsp; the 320-F g=
rind (duration is 268=C2=B0 at 0.050", timing is 57-83&nbsp; &nbsp; 87-53 ,=
 installation figure is then 103=C2=B0 :is that the same as the G5 grind?) =
with 0.340"/8.6mm cam lift and that makes for a&nbsp; valve lift of 12.9mm =
with the 1.55 rocker arms. With 1.65 rockers , valve lift would be 14.2mm a=
nd I could not find valve springs for that lift. The valve springs I used a=
re part no 281003-063.20 from Summit (Isky), 320lb/inch spring rate. They r=
ecommend 0.45"/11.43mm&nbsp; (1.250" - 0.800"from closed to full open posit=
ion, so it is about 1.4mm more in my engine, but there is no problem concer=
ning&nbsp; coil binding : the installed height is a 1mm more than 1.250 , t=
he pressure in closed position is lower&nbsp; of course, but still 34kgs (1=
05kgs at full lift) an that seems to be enough till 7500 rpm</div><div>Race=
torations have a race cam with 7.6mm cam lift, probably that would work wit=
h 1.65 rocker arms. I still have the 1.65 rocker assembly, it is new and it=
 could work with a road cam or any camshaft with a maximum of 8mm cam lift.=
</div><div>Marcel</div><div><br clear=3D"none"></div><hr id=3D"yiv974122051=
1zwchr"><div><b>Van: </b>"fot" &lt;[email-masked]&gt;<br clear=3D"none"=
><b>Aan: </b>"fot" &lt;[email-masked]&gt;<br clear=3D"none"><b>Verzonde=
n: </b>Maandag 10 februari 2020 02:34:27<br clear=3D"none"><b>Onderwerp: </=
b>[Fot] Camshaft recommendation<br clear=3D"none"></div><div><br clear=3D"n=
one"></div><div>
? I will be putting in cam bearings.&nbsp;<div><br clear=3D"none"><div>Than=
p://www.team.net/donate.html<br clear=3D"none">Archive: http://autox.team.n=
et/archive http://www.team.net/pipermail/fot</div><br clear=3D"none">Unsubs=
cribe/Manage: http://autox.team.net/mailman/options/fot/[email-masked]=
om.au<div class=3D"yiv9741220511yqt5723059911" id=3D"yiv9741220511yqtfd7074=
9"><br clear=3D"none"><br clear=3D"none"><br clear=3D"none"></div></div></b=
lockquote></div></div></div><blockquote></blockquote></blockquote></div></d=
iv>
</div><div class=3D"yiv9741220511yqt2182859488" id=3D"yiv9741220511yqt54816=
"></div>_______________________________________________<br clear=3D"none"><=
a rel=3D"nofollow nofollow noopener noreferrer" shape=3D"rect" href=3D"mail=
to:[email-masked]" target=3D"_blank">[email-masked]</a><br clear=3D=
"none"><br clear=3D"none"><a rel=3D"nofollow nofollow noopener noreferrer" =
shape=3D"rect" href=3D"http://www.fot-racing.com" target=3D"_blank">http://=
www.fot-racing.com</a><br clear=3D"none"><br clear=3D"none">Donate: <a rel=
=3D"nofollow nofollow noopener noreferrer" shape=3D"rect" href=3D"http://ww=
w.team.net/donate.html" target=3D"_blank">http://www.team.net/donate.html</=
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on.net</a><br clear=3D"none"><br clear=3D"none"><br clear=3D"none"><br clea=
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---

From: Larry Young via Fot <[email-masked]>
Date: Wed, 19 Feb 2020 15:14:38 -0600

This is a multi-part message in MIME format.
--===============1399881475802161573==
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--------------7FB356F029F10433197FBB69
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I agree with much of what Richard says. The problem with the TR6 engine 
is it has a tiny 0.8" diameter lifter, so as Richard says the higher 
ratio rocker can help to overcome this limitation. As you mention, one 
wants a quick opening (and closing). That means high acceleration. 
Remember Newton's law F = ma? What most people don't realize is that the 
rocker ratio's effect on the forces is squared: (1.65/1.5)^2 = 1.21. So 
the valves and valve springs are effectively 20% heavier. Ideally, to do 
it properly you would develop a grind for the specific rocker ratio. 
That being said, from measuring a number of after market cams, I've 
found most are not particularly aggressive in terms of the acceleration, 
but many smack the lifter hard initially and slam the valve back down on 
the seat (high ramp velocity), which can cause valve bounce and other 
problems. You can find a bit more discussion at my website - 
http://tildentechnologies.com/Cams/CamSprings.html.

Another point. I think people get hung up on valve lift. After all, the 
valve is at maximum lift for an infinitesimal time. I suggest you look 
at the duration the valve is open at intermediate lifts of say 0.20. To 
avoid losing the low end, you want to do this without excessively large 
seat-to-seat duration. For a given seat-to-seat (or 0.050) duration, 
there is no downside to more lift, since it usually produces more 
duration at intermediate lifts.
Cheers,
Larry Young

On 2/12/2020 12:19 PM, van.mulders.marcel--- via Fot wrote:
>
> Richard,
> dare I answer again...
> You say :" first decide what will be the optimum lift for your engine 
> , then... ": in that case : what is the point of high ratio rocker 
> arms, if you want to end at the same maximum valve lift? With a higher 
> lobe x lower rocker ratio, the valve opening speed will be the same 
> and you have a lower force (load) at the pushrods and lobe/cam 
> followers. I think the only reason for a higher rocker ratio is the 
> camfollowers having a too small a diameter to be able to get at the 
> maximum valve lift you want?
> Marcel
> ------------------------------------------------------------------------
> *Van: *"Richard Good" <[email-masked]>
> *Aan: *"van mulders marcel" <[email-masked]>
> *Cc: *"fot" <[email-masked]>
> *Verzonden: *Woensdag 12 februari 2020 17:25:10
> *Onderwerp: *Re: [Fot] Camshaft recommendation
>
> Marcel,
>
> Yes, if you increase rocker ratio and do not change the cam lift, the 
> maximum lift will also increase by 13%.
>
> Richard
>
> Sent from AOL Mobile Mail
> ------------------------------------------------------------------------
> On Wednesday, February 12, 2020 van.mulders.marcel 
> <[email-masked]> wrote:
> Richard,
> dare I answer this...
> Do you mean that, with the higher rocker ratio, the valve is moving 
> faster in the first part of the opening phase and hence moving slower 
> nearing the maximum lift? Suppose the cam lift of both camshafts is 
> such that the maximum lift is 13mm for both the 1.65 and 1.50 ratio 
> and duration at 0.050" is 240°, thus the crank has to move 120° to go 
> from 0.050" lift to maximum lift in both cases. If the valve is 
> opening 13% faster all the way from 0.050" lift untill maximum lift, 
> the maximum lift will also be 13% higher! When an engine is at, say 
> 5000rpm or any other speed, it takes the same time to move 120° (from 
> 0.050" to maximum lift) : the rocker arm ratio does not change that 
> and the valve that is opening 13% faster with the 1.65 ratio will end 
> at a maximum lift that is also 13% higher.
> Marcel
> ------------------------------------------------------------------------
> *Van: *"Richard Good" <[email-masked]>)
> *Aan: *"Michael Zbarsky" <[email-masked]>, 
> [email-masked], "van mulders marcel" 
> <[email-masked]>
>
> *Cc: *"fot" <[email-masked]>
> *Verzonden: *Woensdag 12 februari 2020 02:23:07
> *Onderwerp: *Re: [Fot] Camshaft recommendation
>  7.887
>
> Michael,
>
> People often seem to overlook the main performance benefit of 
> increasing the rocker ratio. That is the increase in valve velocity.  
> The velocity of a flat tappet is limited by it's diameter. If you 
> grind the cam lobe for too much velocity the contact patch will move 
> out past the edge of the lifter and things will self destruct. So 
> tappet velocity is limited.  However, since tappet velocity times 
> rocker ratio equals valve velocity, increasing the rocker ratio will 
> increase valve velocity.
>
> First decide what will be the optimum valve lift for your engine then 
> divide by rocker ratio to determine the net cam lift needed to achieve 
> that valve lift.  Yes, you can grind the cam with a large enough lobe 
> to reach desired lift using stock rockers but you are limited in how 
> fast you can open the valve.  Now if you grind the cam with less lift 
> then use 1.65:1 rockers to reach that same desired valve lift you will 
> be moving the valve about 13% faster. That means it will be open 
> further in a given period of time.  Graph it out and you will see a 
> big difference.  Valve velocity is a huge factor in performance.
>
> I can understand why someone who has tried to use high ratio rockers 
> with a cam that was already maxing out the valve lift with stock 
> rockers would decide that high ratio does not work.  Valve lift was 
> already at max. Increasing it further may be a detriment.  If duration 
> was also maxed out for reasonable torque then the increase in lift 
> during the overlap period caused by the increase in rocker ratio may 
> reduce the low end torque.  Properly applied with the right cam 
> profile, high ratio rockers enable performance that is just not 
> achievable with stock rockers.
>
> Richard Good
> Good Parts Inc
>
> Sent from AOL Mobile Mail
> ------------------------------------------------------------------------
> On Tuesday, February 11, 2020 Michael Zbarsky via Fot 
> <[email-masked]> wrote:
> Thanks everyone! Good stuff. I’m sticking to a redline of just 
> over 6K. I’d also like to keep the 1.65 setup rather than invest in a 
> 1.55 so keep the intel and suggestions coming. The GP3 is a definite 
> contender.
>
> Mike
>
>
>
> On Monday, February 10, 2020, 4:07 PM, Geoff Byrne 
> <[email-masked]> wrote:
>
>     Ditch the 1.65 rockers no good for racing
>     Geoff Byrne
>     TR6 racer down under
>
>     Sent from my iPhone
>
>         On 11 Feb 2020, at 12:52 am, van.mulders.marcel--- via Fot
>         <[email-masked]> wrote:
>
>         I also once bought a Goodparts 1.65 rocker roller assembly for
>         a TR6 engine, but in the end I had to use a 1.55 roller rocker
>         assembly, also from Goodparts, because, with the 1.65, it is
>         difficult to find a race camshaft with a lobe lift that is low
>         enough. With lobes of 8mm or higher, I could not find valve
>         springs to cope with the high valve lift. I bought a G5
>         camshaft from Schneider, they call it  the 320-F grind
>         (duration is 268° at 0.050", timing is 57-83    87-53 ,
>         installation figure is then 103° :is that the same as the G5
>         grind?) with 0.340"/8.6mm cam lift and that makes for a  valve
>         lift of 12.9mm with the 1.55 rocker arms. With 1.65 rockers ,
>         valve lift would be 14.2mm and I could not find valve springs
>         for that lift. The valve springs I used are part no
>         281003-063.20 from Summit (Isky), 320lb/inch spring rate. They
>         recommend 0.45"/11.43mm  (1.250" - 0.800"from closed to full
>         open position, so it is about 1.4mm more in my engine, but
>         there is no problem concerning  coil binding : the installed
>         height is a 1mm more than 1.250 , the pressure in closed
>         position is lower  of course, but still 34kgs (105kgs at full
>         lift) an that seems to be enough till 7500 rpm
>         Racetorations have a race cam with 7.6mm cam lift, probably
>         that would work with 1.65 rocker arms. I still have the 1.65
>         rocker assembly, it is new and it could work with a road cam
>         or any camshaft with a maximum of 8mm cam lift.
>         Marcel
>
>         ------------------------------------------------------------------------
>         *Van: *"fot" <[email-masked]>
>         *Aan: *"fot" <[email-masked]>
>         *Verzonden: *Maandag 10 februari 2020 02:34:27
>         *Onderwerp: *[Fot] Camshaft recommendation
>
>         Hi all, I’m building a TR6 race engine and have a set of 1.65
>         ratio roller rockers from Goodparts. Any recommendations for a
>         suitable camshaft? I will be putting in cam bearings.
>
>         Thanks, Mike
>
>
>
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    I agree with much of what Richard says. The problem with the TR6
    engine is it has a tiny 0.8" diameter lifter, so as Richard says the
    higher ratio rocker can help to overcome this limitation. As you
    mention, one wants a quick opening (and closing). That means high
    acceleration. Remember Newton's law F = ma? What most people don't
    realize is that the rocker ratio's effect on the forces is squared:
    (1.65/1.5)^2 = 1.21. So the valves and valve springs are effectively
    20% heavier. Ideally, to do it properly you would develop a grind
    for the specific rocker ratio. That being said, from measuring a
    number of after market cams, I've found most are not particularly
    aggressive in terms of the acceleration, but many smack the lifter
    hard initially and slam the valve back down on the seat (high ramp
    velocity), which can cause valve bounce and other problems. You can
    find a bit more discussion at my website -
    <a class="moz-txt-link-freetext" href="http://tildentechnologies.com/Cams/CamSprings.html">http://tildentechnologies.com/Cams/CamSprings.html</a>.<br>
    <br>
    Another point. I think people get hung up on valve lift. After all,
    the valve is at maximum lift for an infinitesimal time. I suggest
    you look at the duration the valve is open at intermediate lifts of
    say 0.20. To avoid losing the low end, you want to do this without
    excessively large seat-to-seat duration. For a given seat-to-seat
    (or 0.050) duration, there is no downside to more lift, since it
    usually produces more duration at intermediate lifts.<br>
    Cheers,<br>
    Larry Young<br>
    <br>
    <div class="moz-cite-prefix">On 2/12/2020 12:19 PM,
      van.mulders.marcel--- via Fot wrote:<br>
    </div>
    <blockquote type="cite"
      cite="mid:[email-masked]">
      <meta http-equiv="content-type" content="text/html; charset=UTF-8">
      <div style="font-family: Verdana, Arial, Helvetica, sans-serif;
        font-size: 10pt; color: #000000">
        <div><br>
        </div>
        <div>Richard,</div>
        <div>dare I answer again...</div>
        <div>You say :" first decide what will be the optimum lift for
          your engine , then... ": in that case : what is the point of
          high ratio rocker arms, if you want to end at the same maximum
          valve lift? With a higher lobe x lower rocker ratio, the valve
          opening speed will be the same and you have a lower force
          (load) at the pushrods and lobe/cam followers. I think the
          only reason for a higher rocker ratio is the camfollowers
          having a too small a diameter to be able to get at the maximum
          valve lift you want?</div>
        <div>Marcel</div>
        <hr id="zwchr" data-marker="__DIVIDER__">
        <div data-marker="__HEADERS__"><b>Van: </b>"Richard Good"
          <a class="moz-txt-link-rfc2396E" href="mailto:[email-masked]">&lt;[email-masked]&gt;</a><br>
          <b>Aan: </b>"van mulders marcel"
          <a class="moz-txt-link-rfc2396E" href="mailto:[email-masked]">&lt;[email-masked]&gt;</a><br>
          <b>Cc: </b>"fot" <a class="moz-txt-link-rfc2396E" href="mailto:[email-masked]">&lt;[email-masked]&gt;</a><br>
          <b>Verzonden: </b>Woensdag 12 februari 2020 17:25:10<br>
          <b>Onderwerp: </b>Re: [Fot] Camshaft recommendation<br>
        </div>
        <div><br>
        </div>
        <div data-marker="__QUOTED_TEXT__">
          <p dir="ltr">Marcel,</p>
          <p dir="ltr">Yes, if you increase rocker ratio and do not
            change the cam lift, the maximum lift will also increase by
            13%.</p>
          <p dir="ltr">Richard</p>
          <p dir="ltr">Sent from AOL Mobile Mail <br>
            Get the new AOL app: mail.mobile.aol.com</p>
          <hr
style="border:0;height:1px;color:#999;background-color:#999;width:100%;margin:0
            0 9px 0;padding:0"><span
            style="font-size:14px;color:#999999">On Wednesday, February
            12, 2020 van.mulders.marcel &lt;<span style="color:#0000a0"><a class="moz-txt-link-abbreviated" href="mailto:[email-masked]">[email-masked]</a></span>&gt;
            wrote:</span><br>
          <div>
            <div style="font-family:'verdana' , 'arial' , 'helvetica' ,
              sans-serif;font-size:10pt;color:#000000">
              <div>Richard, </div>
              <div>dare I answer this...</div>
              <div>Do you mean that, with the higher rocker ratio, the
                valve is moving faster in the first part of the opening
                phase and hence moving slower nearing the maximum lift?
                Suppose the cam lift of both camshafts is such that the
                maximum lift is 13mm for both the 1.65 and 1.50 ratio
                and duration at 0.050" is 240°, thus the crank has to
                move 120° to go from 0.050" lift to maximum lift in both
                cases. If the valve is opening 13% faster all the way
                from 0.050" lift untill maximum lift, the maximum lift
                will also be 13% higher! When an engine is at, say
                5000rpm or any other speed, it takes the same time to
                move 120° (from 0.050" to maximum lift) : the rocker arm
                ratio does not change that and the valve that is opening
                13% faster with the 1.65 ratio will end at a maximum
                lift that is also 13% higher. </div>
              <div>Marcel</div>
              <hr id="yiv9741220511zwchr">
              <div><b>Van: </b>"Richard Good"
                <a class="moz-txt-link-rfc2396E" href="mailto:[email-masked]">&lt;[email-masked]&gt;</a>)<br clear="none">
                <b>Aan: </b>"Michael Zbarsky"
                <a class="moz-txt-link-rfc2396E" href="mailto:[email-masked]">&lt;[email-masked]&gt;</a>, <a class="moz-txt-link-abbreviated" href="mailto:[email-masked]">[email-masked]</a>,
                "van mulders marcel"
                <a class="moz-txt-link-rfc2396E" href="mailto:[email-masked]">&lt;[email-masked]&gt;</a>
                <div class="yiv9741220511yqt0090589858"
                  id="yiv9741220511yqtfd74605"><br clear="none">
                  <b>Cc: </b>"fot" <a class="moz-txt-link-rfc2396E" href="mailto:[email-masked]">&lt;[email-masked]&gt;</a><br
                    clear="none">
                  <b>Verzonden: </b>Woensdag 12 februari 2020 02:23:07<br
                    clear="none">
                  <b>Onderwerp: </b>Re: [Fot] Camshaft recommendation<br
                    clear="none">
                </div>
              </div>
              <div class="yiv9741220511yqt0090589858"
                id="yiv9741220511yqtfd30775">
                <div> 7.887</div>
                <div>
                  <p dir="ltr">Michael,</p>
                  <p dir="ltr">People often seem to overlook the main
                    performance benefit of increasing the rocker ratio. 
                    That is the increase in valve velocity.  The
                    velocity of a flat tappet is limited by it's
                    diameter. If you grind the cam lobe for too much
                    velocity the contact patch will move out past the
                    edge of the lifter and things will self destruct. 
                    So tappet velocity is limited.  However, since
                    tappet velocity times rocker ratio equals valve
                    velocity, increasing the rocker ratio will increase
                    valve velocity.</p>
                  <p dir="ltr">First decide what will be the optimum
                    valve lift for your engine then divide by rocker
                    ratio to determine the net cam lift needed to
                    achieve that valve lift.  Yes, you can grind the cam
                    with a large enough lobe to reach desired lift using
                    stock rockers but you are limited in how fast you
                    can open the valve.  Now if you grind the cam with
                    less lift then use 1.65:1 rockers to reach that same
                    desired valve lift you will be moving the valve
                    about 13% faster. That means it will be open further
                    in a given period of time.  Graph it out and you
                    will see a big difference.  Valve velocity is a huge
                    factor in performance.  </p>
                  <p dir="ltr">I can understand why someone who has
                    tried to use high ratio rockers with a cam that was
                    already maxing out the valve lift with stock rockers
                    would decide that high ratio does not work.  Valve
                    lift was already at max. Increasing it further may
                    be a detriment.  If duration was also maxed out for
                    reasonable torque then the increase in lift during
                    the overlap period caused by the increase in rocker
                    ratio may reduce the low end torque.  Properly
                    applied with the right cam profile, high ratio
                    rockers enable performance that is just not
                    achievable with stock rockers.</p>
                  <p dir="ltr">Richard Good<br clear="none">
                    Good Parts Inc</p>
                  <p dir="ltr">Sent from AOL Mobile Mail <br
                      clear="none">
                    Get the new AOL app: mail.mobile.aol.com</p>
                  <hr
style="border:0;min-height:1px;color:#999;background-color:#999;width:100%;margin:0
                    0 9px 0;padding:0"><span
                    style="font-size:14px;color:#999999">On Tuesday,
                    February 11, 2020 Michael Zbarsky via Fot &lt;<span
                      style="color:#0000a0"><a class="moz-txt-link-abbreviated" href="mailto:[email-masked]">[email-masked]</a></span>&gt;
                    wrote:</span><br clear="none">
                  <div>
                    Thanks everyone! Good stuff. I’m sticking to a
                    redline of just over 6K. I’d also like to keep the
                    1.65 setup rather than invest in a 1.55 so keep the
                    intel and suggestions coming. The GP3 is a definite
                    contender. 
                    <div><br clear="none">
                    </div>
                    <div>Mike <br clear="none">
                      <br clear="none">
                      <br clear="none">
                      <br clear="none">
                      <div class="yiv9741220511yqt2182859488"
                        id="yiv9741220511yqt21880">
                        <p class="yiv9741220511yahoo-quoted-begin"
                          style="font-size:15px;color:#715ffa;padding-top:15px;margin-top:0">On
                          Monday, February 10, 2020, 4:07 PM, Geoff
                          Byrne <a class="moz-txt-link-rfc2396E" href="mailto:[email-masked]">&lt;[email-masked]&gt;</a> wrote:</p>
                        <blockquote class="yiv9741220511iosymail">
                          <div id="yiv9741220511">
                            <div>Ditch the 1.65 rockers no good for
                              racing
                              <div>Geoff Byrne</div>
                              <div>TR6 racer down under<br clear="none">
                                <br clear="none">
                                <div dir="ltr">Sent from my iPhone</div>
                                <div dir="ltr"><br clear="none">
                                  <blockquote>On 11 Feb 2020, at 12:52
                                    am, van.mulders.marcel--- via Fot
                                    <a class="moz-txt-link-rfc2396E" href="mailto:[email-masked]">&lt;[email-masked]&gt;</a> wrote:<br
                                      clear="none">
                                    <br clear="none">
                                  </blockquote>
                                </div>
                                <blockquote>
                                  <div dir="ltr">
                                    <div style="font-family:'verdana' ,
                                      'arial' , 'helvetica' ,
                                      sans-serif;font-size:10pt;color:#000000">
                                      <div>I also once bought a
                                        Goodparts 1.65 rocker roller
                                        assembly for a TR6 engine, but
                                        in the end I had to use a 1.55
                                        roller rocker assembly, also
                                        from Goodparts, because, with
                                        the 1.65, it is difficult to
                                        find a race camshaft with a 
                                        lobe lift that is low enough.
                                        With lobes of 8mm or higher, I
                                        could not find valve springs to
                                        cope with the high valve lift. I
                                        bought a G5 camshaft from
                                        Schneider, they call it  the
                                        320-F grind (duration is 268° at
                                        0.050", timing is 57-83    87-53
                                        , installation figure is then
                                        103° :is that the same as the G5
                                        grind?) with 0.340"/8.6mm cam
                                        lift and that makes for a  valve
                                        lift of 12.9mm with the 1.55
                                        rocker arms. With 1.65 rockers ,
                                        valve lift would be 14.2mm and I
                                        could not find valve springs for
                                        that lift. The valve springs I
                                        used are part no 281003-063.20
                                        from Summit (Isky), 320lb/inch
                                        spring rate. They recommend
                                        0.45"/11.43mm  (1.250" -
                                        0.800"from closed to full open
                                        position, so it is about 1.4mm
                                        more in my engine, but there is
                                        no problem concerning  coil
                                        binding : the installed height
                                        is a 1mm more than 1.250 , the
                                        pressure in closed position is
                                        lower  of course, but still
                                        34kgs (105kgs at full lift) an
                                        that seems to be enough till
                                        7500 rpm</div>
                                      <div>Racetorations have a race cam
                                        with 7.6mm cam lift, probably
                                        that would work with 1.65 rocker
                                        arms. I still have the 1.65
                                        rocker assembly, it is new and
                                        it could work with a road cam or
                                        any camshaft with a maximum of
                                        8mm cam lift.</div>
                                      <div>Marcel</div>
                                      <div><br clear="none">
                                      </div>
                                      <hr id="yiv9741220511zwchr">
                                      <div><b>Van: </b>"fot"
                                        <a class="moz-txt-link-rfc2396E" href="mailto:[email-masked]">&lt;[email-masked]&gt;</a><br
                                          clear="none">
                                        <b>Aan: </b>"fot"
                                        <a class="moz-txt-link-rfc2396E" href="mailto:[email-masked]">&lt;[email-masked]&gt;</a><br
                                          clear="none">
                                        <b>Verzonden: </b>Maandag 10
                                        februari 2020 02:34:27<br
                                          clear="none">
                                        <b>Onderwerp: </b>[Fot]
                                        Camshaft recommendation<br
                                          clear="none">
                                      </div>
                                      <div><br clear="none">
                                      </div>
                                      <div>
                                        Hi all, I’m building a TR6 race
                                        engine and have a set of 1.65
                                        ratio roller rockers from
                                        Goodparts. Any recommendations
                                        for a suitable camshaft? I will
                                        be putting in cam bearings. 
                                        <div><br clear="none">
                                          <div>Thanks, Mike<br
                                              clear="none">
                                            <br clear="none">
                                            <br clear="none">
                                          </div>
                                        </div>
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---

From: Duncan Charlton via Fot <[email-masked]>
Date: Wed, 19 Feb 2020 17:43:44 -0600

--===============4806931183855281534==

--5e4dc835_167a3623_4eb

I set my rocker pedestals a bit higher and used longer pushrods on my BMC=
 A-series engine. =C2=A0I was willing to give up some maximum lift in ord=
er to get quicker valve acceleration at low lift. =C2=A0By raising the pe=
destals, the (roller-tip) rocker arms achieve a 90=CB=9A angle to the val=
ve stem before half-lift is reached. =C2=A0I reason that this should give=
 me more area under the curve and greater torque.

Duncan
On =46eb 19, 2020, 3:15 PM -0600, Larry Young via =46ot <fot=40autox.team=
.net>, wrote:
> I agree with much of what Richard says. The problem with the TR6 engine=
 is it has a tiny 0.8=22 diameter lifter, so as Richard says the higher r=
atio rocker can help to overcome this limitation. As you mention, one wan=
ts a quick opening (and closing). That means high acceleration. Remember =
Newton's law =46 =3D ma=3F What most people don't realize is that the roc=
ker ratio's effect on the forces is squared: (1.65/1.5)=5E2 =3D 1.21. So =
the valves and valve springs are effectively 20% heavier. Ideally, to do =
it properly you would develop a grind for the specific rocker ratio. That=
 being said, from measuring a number of after market cams, I've found mos=
t are not particularly aggressive in terms of the acceleration, but many =
smack the lifter hard initially and slam the valve back down on the seat =
(high ramp velocity), which can cause valve bounce and other problems. Yo=
u can find a bit more discussion at my website - http://tildentechnologie=
s.com/Cams/CamSprings.html.
>
> Another point. I think people get hung up on valve lift. After all, the=
 valve is at maximum lift for an infinitesimal time. I suggest you look a=
t the duration the valve is open at intermediate lifts of say 0.20. To av=
oid losing the low end, you want to do this without excessively large sea=
t-to-seat duration. =46or a given seat-to-seat (or 0.050) duration, there=
 is no downside to more lift, since it usually produces more duration at =
intermediate lifts.
> Cheers,
> Larry Young
>
> On 2/12/2020 12:19 PM, van.mulders.marcel--- via =46ot wrote:
> >
> > Richard,
> > dare I answer again...
> > You say :=22 first decide what will be the optimum lift for your engi=
ne , then... =22: in that case : what is the point of high ratio rocker a=
rms, if you want to end at the same maximum valve lift=3F With a higher l=
obe x lower rocker ratio, the valve opening speed will be the same and yo=
u have a lower force (load) at the pushrods and lobe/cam followers. I thi=
nk the only reason for a higher rocker ratio is the camfollowers having a=
 too small a diameter to be able to get at the maximum valve lift you wan=
t=3F
> > Marcel
> > Van: =22Richard Good=22 <goodparts=40verizon.net>
> > Aan: =22van mulders marcel=22 <van.mulders.marcel=40telenet.be>
> > Cc: =22fot=22 <fot=40autox.team.net>
> > Verzonden: Woensdag 12 februari 2020 17:25:10
> > Onderwerp: Re: =5B=46ot=5D Camshaft recommendation
> >
> > Marcel,
> > Yes, if you increase rocker ratio and do not change the cam lift, the=
> > On Wednesday, =46ebruary 12, 2020 van.mulders.marcel <van.mulders.mar=
cel=40telenet.be> wrote:
> > Richard,
> > dare I answer this...
> > Do you mean that, with the higher rocker ratio, the valve is moving f=
aster in the first part of the opening phase and hence moving slower near=
ing the maximum lift=3F Suppose the cam lift of both camshafts is such th=
at the maximum lift is 13mm for both the 1.65 and 1.50 ratio and duration=
 at 0.050=22 is 240=C2=B0, thus the crank has to move 120=C2=B0 to go fro=
m 0.050=22 lift to maximum lift in both cases. If the valve is opening 13=
% faster all the way from 0.050=22 lift untill maximum lift, the maximum =
lift will also be 13% higher=21 When an engine is at, say 5000rpm or any =
other speed, it takes the same time to move 120=C2=B0 (from 0.050=22 to m=
aximum lift) : the rocker arm ratio does not change that and the valve th=
at is opening 13% faster with the 1.65 ratio will end at a maximum lift t=
hat is also 13% higher.
> > Marcel
> > Van: =22Richard Good=22 <goodparts=40verizon.net>)
> > Aan: =22Michael Zbarsky=22 <mzbarsky=40yahoo.com>, gkbyrne=40optusnet=
.com.au, =22van mulders marcel=22 <van.mulders.marcel=40telenet.be>
> >
> > Cc: =22fot=22 <fot=40autox.team.net>
> > Onderwerp: Re: =5B=46ot=5D Camshaft recommendation
> > =C2=A07.887
> > Michael,
> > People often seem to overlook the main performance benefit of increas=
ing the rocker ratio.=C2=A0 That is the increase in valve velocity.=C2=A0=
 The velocity of a flat tappet is limited by it's diameter. If you grind =
the cam lobe for too much velocity the contact patch will move out past t=
he edge of the lifter and things will self destruct.=C2=A0 So tappet velo=
city is limited.=C2=A0 However, since tappet velocity times rocker ratio =
equals valve velocity, increasing the rocker ratio will increase valve ve=
locity.
> > =46irst decide what will be the optimum valve lift for your engine th=
en divide by rocker ratio to determine the net cam lift needed to achieve=
 that valve lift.=C2=A0 Yes, you can grind the cam with a large enough lo=
be to reach desired lift using stock rockers but you are limited in how f=
ast you can open the valve.=C2=A0 Now if you grind the cam with less lift=
 then use 1.65:1 rockers to reach that same desired valve lift you will b=
e moving the valve about 13% faster. That means it will be open further i=
n a given period of time.=C2=A0 Graph it out and you will see a big diffe=
rence.=C2=A0 Valve velocity is a huge factor in performance.
> > I can understand why someone who has tried to use high ratio rockers =
with a cam that was already maxing out the valve lift with stock rockers =
would decide that high ratio does not work.=C2=A0 Valve lift was already =
at max. Increasing it further may be a detriment.=C2=A0 If duration was a=
lso maxed out for reasonable torque then the increase in lift during the =
overlap period caused by the increase in rocker ratio may reduce the low =
end torque.=C2=A0 Properly applied with the right cam profile, high ratio=
 rockers enable performance that is just not achievable with stock rocker=
s.
> > On Tuesday, =46ebruary 11, 2020 Michael Zbarsky via =46ot <mzbarsky=40=
yahoo.com> wrote:
> > Thanks everyone=21 Good stuff. I=E2=80=99m sticking to a redline of j=
ust over=C2=A06K. I=E2=80=99d also like to keep the 1.65 setup rather tha=
n invest in a 1.55 so keep the intel and=C2=A0suggestions coming. The GP3=
 is a definite contender.
> >
> > Mike
> >
> >
> >
> > On Monday, =46ebruary 10, 2020, 4:07 PM, Geoff Byrne <gkbyrne=40optus=
net.com.au> wrote:
> > > > On 11 =46eb 2020, at 12:52 am, van.mulders.marcel--- via =46ot <f=
ot=40autox.team.net> wrote:
> > > >
> > > > I also once bought a Goodparts 1.65 rocker roller assembly for a =
TR6 engine, but in the end I had to use a 1.55 roller rocker assembly, al=
so from Goodparts, because, with the 1.65, it is difficult to find a race=
 camshaft with a=C2=A0 lobe lift that is low enough. With lobes of 8mm or=
 higher, I could not find valve springs to cope with the high valve lift.=
 I bought a G5 camshaft from Schneider, they call it=C2=A0 the 320-=46 gr=
ind (duration is 268=C2=B0 at 0.050=22, timing is 57-83=C2=A0 =C2=A0 87-5=
3 , installation figure is then 103=C2=B0 :is that the same as the G5 gri=
nd=3F) with 0.340=22/8.6mm cam lift and that makes for a=C2=A0 valve lift=
 of 12.9mm with the 1.55 rocker arms. With 1.65 rockers , valve lift woul=
d be 14.2mm and I could not find valve springs for that lift. The valve s=
prings I used are part no 281003-063.20 from Summit (Isky), 320lb/inch sp=
ring rate. They recommend 0.45=22/11.43mm=C2=A0 (1.250=22 - 0.800=22from =
closed to full open position, so it is about 1.4mm more in my engine, but=
 there is no problem concerning=C2=A0 coil binding : the installed height=
 is a 1mm more than 1.250 , the pressure in closed position is lower=C2=A0=
 of course, but still 34kgs (105kgs at full lift) an that seems to be eno=
ugh till 7500 rpm
> > > > Racetorations have a race cam with 7.6mm cam lift, probably that =
would work with 1.65 rocker arms. I still have the 1.65 rocker assembly, =
it is new and it could work with a road cam or any camshaft with a maximu=
m of 8mm cam lift.
> > > > Marcel
> > > >
> > > > Van: =22fot=22 <fot=40autox.team.net>
> > > > Aan: =22fot=22 <fot=40autox.team.net>
> > > > Onderwerp: =5B=46ot=5D Camshaft recommendation
> > > >
> > > > Hi all, I=E2=80=99m building a TR6 race engine and have a set of =
1.65 ratio roller rockers from Goodparts. Any recommendations for a suita=
ble camshaft=3F I will be putting in cam bearings.
> > > >
> > > > Thanks, Mike
> > > >
> > > >
> > > >
> > > > =5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=
=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=

> > > > fot=40autox.team.net
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ail/fot
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.mulders.marcel=40telenet.be
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> > > > =5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=
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> > =5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=
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--5e4dc835_167a3623_4eb

<html xmlns=3D=22http://www.w3.org/1999/xhtml=22>
<head>
<title></title>
</head>
<body>
<div name=3D=22messageBodySection=22><font face=3D=22Helvetica, sans-seri=
f=22>I set my rocker pedestals a bit higher and used longer pushrods on m=
y BMC A-series engine. &=23160;I was willing to give up some maximum lift=
 in order to get quicker valve acceleration at low lift. &=23160;By raisi=
ng the pedestals, the (roller-tip) rocker arms achieve a 90=CB=9A angle t=
o the valve stem before half-lift is reached. &=23160;I reason that this =
should give me more area under the curve and greater torque.</font></div>=

<div name=3D=22messageSignatureSection=22><br />
<div class=3D=22match=46ont=22>Duncan</div>
</div>
<div name=3D=22messageReplySection=22>On =46eb 19, 2020, 3:15 PM -0600, L=
arry Young via =46ot &lt;fot=40autox.team.net&gt;, wrote:<br />
<blockquote type=3D=22cite=22 class=3D=22spark=5Fquote=22 style=3D=22marg=
in: 5px 5px; padding-left: 10px; border-left: thin solid =231abc9c;=22>I =
agree with much of what Richard says. The problem with the TR6 engine is =
it has a tiny 0.8=22 diameter lifter, so as Richard says the higher ratio=
 rocker can help to overcome this limitation. As you mention, one wants a=
 quick opening (and closing). That means high acceleration. Remember Newt=
on's law =46 =3D ma=3F What most people don't realize is that the rocker =
ratio's effect on the forces is squared: (1.65/1.5)=5E2 =3D 1.21. So the =
valves and valve springs are effectively 20% heavier. Ideally, to do it p=
roperly you would develop a grind for the specific rocker ratio. That bei=
ng said, from measuring a number of after market cams, I've found most ar=
e not particularly aggressive in terms of the acceleration, but many smac=
k the lifter hard initially and slam the valve back down on the seat (hig=
h ramp velocity), which can cause valve bounce and other problems. You ca=
n find a bit more discussion at my website - <a class=3D=22moz-txt-link-f=
reetext=22 href=3D=22http://tildentechnologies.com/Cams/CamSprings.html=22=
>http://tildentechnologies.com/Cams/CamSprings.html</a>.<br />
<br />
Another point. I think people get hung up on valve lift. After all, the v=
alve is at maximum lift for an infinitesimal time. I suggest you look at =
the duration the valve is open at intermediate lifts of say 0.20. To avoi=
d losing the low end, you want to do this without excessively large seat-=
to-seat duration. =46or a given seat-to-seat (or 0.050) duration, there i=
s no downside to more lift, since it usually produces more duration at in=
termediate lifts.<br />
Cheers,<br />
Larry Young<br />
<br />
<div class=3D=22moz-cite-prefix=22>On 2/12/2020 12:19 PM, van.mulders.mar=
cel--- via =46ot wrote:<br /></div>
<blockquote type=3D=22cite=22 cite=3D=22mid:1392309332.69004004.158153159=
8578.JavaMail.zimbra=40telenet.be=22 class=3D=22spark=5Fquote=22 style=3D=
=22margin: 5px 5px; padding-left: 10px; border-left: thin solid =23e67e22=
;=22>
<meta http-equiv=3D=22content-type=22 content=3D=22text/html; charset=3DU=
T=46-8=22 />
<div style=3D=22font-family: Verdana, Arial, Helvetica, sans-serif; font-=
size: 10pt; color: =23000000=22>
<div><br /></div>
<div>Richard,</div>
<div>dare I answer again...</div>
<div>You say :=22 first decide what will be the optimum lift for your eng=
ine , then... =22: in that case : what is the point of high ratio rocker =
arms, if you want to end at the same maximum valve lift=3F With a higher =
lobe x lower rocker ratio, the valve opening speed will be the same and y=
ou have a lower force (load) at the pushrods and lobe/cam followers. I th=
ink the only reason for a higher rocker ratio is the camfollowers having =
a too small a diameter to be able to get at the maximum valve lift you wa=
nt=3F</div>
<div>Marcel</div>
<hr id=3D=22zwchr=22 data-marker=3D=22=5F=5FDIVIDER=5F=5F=22 />
<div data-marker=3D=22=5F=5FHEADERS=5F=5F=22><b>Van:</b> =22Richard Good=22=
 <a class=3D=22moz-txt-link-rfc2396E=22 href=3D=22mailto:goodparts=40veri=
zon.net=22>&lt;goodparts=40verizon.net&gt;</a><br />
<b>Aan:</b> =22van mulders marcel=22 <a class=3D=22moz-txt-link-rfc2396E=22=
 href=3D=22mailto:van.mulders.marcel=40telenet.be=22>&lt;van.mulders.marc=
el=40telenet.be&gt;</a><br />
<b>Cc:</b> =22fot=22 <a class=3D=22moz-txt-link-rfc2396E=22 href=3D=22mai=
lto:fot=40autox.team.net=22>&lt;fot=40autox.team.net&gt;</a><br />
<b>Verzonden:</b> Woensdag 12 februari 2020 17:25:10<br />
<b>Onderwerp:</b> Re: =5B=46ot=5D Camshaft recommendation<br /></div>
<div><br /></div>
<div data-marker=3D=22=5F=5FQUOTED=5FTEXT=5F=5F=22>
<p dir=3D=22ltr=22>Marcel,</p>
<p dir=3D=22ltr=22>Yes, if you increase rocker ratio and do not change th=
e cam lift, the maximum lift will also increase by 13%.</p>
<p dir=3D=22ltr=22>Richard</p>
<p dir=3D=22ltr=22>Sent from AOL Mobile Mail<br />
Get the new AOL app: mail.mobile.aol.com</p>
<hr style=3D=22border:0;height:1px;color:=23999;background-color:=23999;w=
idth:100%;margin:0 0 9px 0;padding:0=22 />
<span style=3D=22font-size:14px;color:=23999999=22>On Wednesday, =46ebrua=
ry 12, 2020 van.mulders.marcel &lt;<span style=3D=22color:=230000a0=22><a=
 class=3D=22moz-txt-link-abbreviated=22 href=3D=22mailto:van.mulders.marc=
el=40telenet.be=22>van.mulders.marcel=40telenet.be</a></span>&gt; wrote:<=
/span><br />
<div>
<div style=3D=22font-family:'verdana' , 'arial' , 'helvetica' , sans-seri=
f;font-size:10pt;color:=23000000=22>
<div>Richard,&=23160;</div>
<div>dare I answer this...</div>
<div>Do you mean that, with the higher rocker ratio, the valve is moving =
faster in the first part of the opening phase and hence moving slower nea=
ring the maximum lift=3F Suppose the cam lift of both camshafts is such t=
hat the maximum lift is 13mm for both the 1.65 and 1.50 ratio and duratio=
n at 0.050=22 is 240=C2=B0, thus the crank has to move 120=C2=B0 to go fr=
om 0.050=22 lift to maximum lift in both cases. If the valve is opening 1=
3% faster all the way from 0.050=22 lift untill maximum lift, the maximum=
 lift will also be 13% higher=21 When an engine is at, say 5000rpm or any=
 other speed, it takes the same time to move 120=C2=B0 (from 0.050=22 to =
maximum lift) : the rocker arm ratio does not change that and the valve t=
hat is opening 13% faster with the 1.65 ratio will end at a maximum lift =
that is also 13% higher.&=23160;</div>
<div>Marcel</div>
<hr id=3D=22yiv9741220511zwchr=22 />
<div><b>Van:</b> =22Richard Good=22 <a class=3D=22moz-txt-link-rfc2396E=22=
 href=3D=22mailto:goodparts=40verizon.net=22>&lt;goodparts=40verizon.net&=
gt;</a>)<br clear=3D=22none=22 />
<b>Aan:</b> =22Michael Zbarsky=22 <a class=3D=22moz-txt-link-rfc2396E=22 =
href=3D=22mailto:mzbarsky=40yahoo.com=22>&lt;mzbarsky=40yahoo.com&gt;</a>=
, <a class=3D=22moz-txt-link-abbreviated=22 href=3D=22mailto:gkbyrne=40op=
tusnet.com.au=22>gkbyrne=40optusnet.com.au</a>, =22van mulders marcel=22 =
<a class=3D=22moz-txt-link-rfc2396E=22 href=3D=22mailto:van.mulders.marce=
l=40telenet.be=22>&lt;van.mulders.marcel=40telenet.be&gt;</a>
<div class=3D=22yiv9741220511yqt0090589858=22 id=3D=22yiv9741220511yqtfd7=
4605=22><br clear=3D=22none=22 />
<b>Cc:</b> =22fot=22 <a class=3D=22moz-txt-link-rfc2396E=22 href=3D=22mai=
lto:fot=40autox.team.net=22>&lt;fot=40autox.team.net&gt;</a><br clear=3D=22=
none=22 />
<b>Verzonden:</b> Woensdag 12 februari 2020 02:23:07<br clear=3D=22none=22=
 />
<b>Onderwerp:</b> Re: =5B=46ot=5D Camshaft recommendation<br clear=3D=22n=
one=22 /></div>
</div>
<div class=3D=22yiv9741220511yqt0090589858=22 id=3D=22yiv9741220511yqtfd3=
0775=22>
<div>&=23160;7.887</div>
<div>
<p dir=3D=22ltr=22>Michael,</p>
<p dir=3D=22ltr=22>People often seem to overlook the main performance ben=
efit of increasing the rocker ratio.&=23160; That is the increase in valv=
e velocity.&=23160; The velocity of a flat tappet is limited by it's diam=
eter. If you grind the cam lobe for too much velocity the contact patch w=
ill move out past the edge of the lifter and things will self destruct.&=23=
160; So tappet velocity is limited.&=23160; However, since tappet velocit=
y times rocker ratio equals valve velocity, increasing the rocker ratio w=
ill increase valve velocity.</p>
<p dir=3D=22ltr=22>=46irst decide what will be the optimum valve lift for=
 your engine then divide by rocker ratio to determine the net cam lift ne=
eded to achieve that valve lift.&=23160; Yes, you can grind the cam with =
a large enough lobe to reach desired lift using stock rockers but you are=
 limited in how fast you can open the valve.&=23160; Now if you grind the=
 cam with less lift then use 1.65:1 rockers to reach that same desired va=
lve lift you will be moving the valve about 13% faster. That means it wil=
l be open further in a given period of time.&=23160; Graph it out and you=
 will see a big difference.&=23160; Valve velocity is a huge factor in pe=
rformance.&=23160;</p>
<p dir=3D=22ltr=22>I can understand why someone who has tried to use high=
 ratio rockers with a cam that was already maxing out the valve lift with=
 stock rockers would decide that high ratio does not work.&=23160; Valve =
lift was already at max. Increasing it further may be a detriment.&=23160=
; If duration was also maxed out for reasonable torque then the increase =
in lift during the overlap period caused by the increase in rocker ratio =
may reduce the low end torque.&=23160; Properly applied with the right ca=
m profile, high ratio rockers enable performance that is just not achieva=
ble with stock rockers.</p>
<p dir=3D=22ltr=22>Richard Good<br clear=3D=22none=22 />
Good Parts Inc</p>
<p dir=3D=22ltr=22>Sent from AOL Mobile Mail<br clear=3D=22none=22 />
Get the new AOL app: mail.mobile.aol.com</p>
<hr style=3D=22border:0;min-height:1px;color:=23999;background-color:=239=
99;width:100%;margin:0 0 9px 0;padding:0=22 />
<span style=3D=22font-size:14px;color:=23999999=22>On Tuesday, =46ebruary=
 11, 2020 Michael Zbarsky via =46ot &lt;<span style=3D=22color:=230000a0=22=
><a class=3D=22moz-txt-link-abbreviated=22 href=3D=22mailto:mzbarsky=40ya=
hoo.com=22>mzbarsky=40yahoo.com</a></span>&gt; wrote:</span><br clear=3D=22=
none=22 />
<div>Thanks everyone=21 Good stuff. I=E2=80=99m sticking to a redline of =
just over&=23160;6K. I=E2=80=99d also like to keep the 1.65 setup rather =
than invest in a 1.55 so keep the intel and&=23160;suggestions coming. Th=
e GP3 is a definite contender.&=23160;
<div><br clear=3D=22none=22 /></div>
<div>Mike&=23160;<br clear=3D=22none=22 />
<br clear=3D=22none=22 />
<br clear=3D=22none=22 />
<br clear=3D=22none=22 />
<div class=3D=22yiv9741220511yqt2182859488=22 id=3D=22yiv9741220511yqt218=
80=22>
<p class=3D=22yiv9741220511yahoo-quoted-begin=22 style=3D=22font-size:15p=
x;color:=23715ffa;padding-top:15px;margin-top:0=22>On Monday, =46ebruary =
10, 2020, 4:07 PM, Geoff Byrne <a class=3D=22moz-txt-link-rfc2396E=22 hre=
f=3D=22mailto:gkbyrne=40optusnet.com.au=22>&lt;gkbyrne=40optusnet.com.au&=
gt;</a> wrote:</p>
<blockquote class=3D=22yiv9741220511iosymail spark=5Fquote=22 style=3D=22=
margin: 5px 5px; padding-left: 10px; border-left: thin solid =233498db;=22=
<div id=3D=22yiv9741220511=22>
<div>Ditch the 1.65 rockers no good for racing
<div>Geoff Byrne</div>
<div>TR6 racer down under<br clear=3D=22none=22 />
<br clear=3D=22none=22 />
<div dir=3D=22ltr=22>Sent from my iPhone</div>
<div dir=3D=22ltr=22><br clear=3D=22none=22 />
<blockquote class=3D=22spark=5Fquote=22 style=3D=22margin: 5px 5px; paddi=
ng-left: 10px; border-left: thin solid =23d35400;=22>On 11 =46eb 2020, at=
 12:52 am, van.mulders.marcel--- via =46ot <a class=3D=22moz-txt-link-rfc=
2396E=22 href=3D=22mailto:fot=40autox.team.net=22>&lt;fot=40autox.team.ne=
t&gt;</a> wrote:<br clear=3D=22none=22 />
<br clear=3D=22none=22 /></blockquote>
</div>
<blockquote class=3D=22spark=5Fquote=22 style=3D=22margin: 5px 5px; paddi=
ng-left: 10px; border-left: thin solid =23d35400;=22>
<div dir=3D=22ltr=22>
<div style=3D=22font-family:'verdana' , 'arial' , 'helvetica' , sans-seri=
f;font-size:10pt;color:=23000000=22>
<div>I also once bought a Goodparts 1.65 rocker roller assembly for a TR6=
 engine, but in the end I had to use a 1.55 roller rocker assembly, also =
from Goodparts, because, with the 1.65, it is difficult to find a race ca=
mshaft with a&=23160; lobe lift that is low enough. With lobes of 8mm or =
higher, I could not find valve springs to cope with the high valve lift. =
I bought a G5 camshaft from Schneider, they call it&=23160; the 320-=46 g=
rind (duration is 268=C2=B0 at 0.050=22, timing is 57-83&=23160; &=23160;=
 87-53 , installation figure is then 103=C2=B0 :is that the same as the G=
5 grind=3F) with 0.340=22/8.6mm cam lift and that makes for a&=23160; val=
ve lift of 12.9mm with the 1.55 rocker arms. With 1.65 rockers , valve li=
ft would be 14.2mm and I could not find valve springs for that lift. The =
valve springs I used are part no 281003-063.20 from Summit (Isky), 320lb/=
inch spring rate. They recommend 0.45=22/11.43mm&=23160; (1.250=22 - 0.80=
0=22from closed to full open position, so it is about 1.4mm more in my en=
gine, but there is no problem concerning&=23160; coil binding : the insta=
lled height is a 1mm more than 1.250 , the pressure in closed position is=
 lower&=23160; of course, but still 34kgs (105kgs at full lift) an that s=
eems to be enough till 7500 rpm</div>
<div>Racetorations have a race cam with 7.6mm cam lift, probably that wou=
ld work with 1.65 rocker arms. I still have the 1.65 rocker assembly, it =
is new and it could work with a road cam or any camshaft with a maximum o=
f 8mm cam lift.</div>
<div>Marcel</div>
<div><br clear=3D=22none=22 /></div>
<hr id=3D=22yiv9741220511zwchr=22 />
<div><b>Van:</b> =22fot=22 <a class=3D=22moz-txt-link-rfc2396E=22 href=3D=
=22mailto:fot=40autox.team.net=22>&lt;fot=40autox.team.net&gt;</a><br cle=
ar=3D=22none=22 />
<b>Aan:</b> =22fot=22 <a class=3D=22moz-txt-link-rfc2396E=22 href=3D=22ma=
ilto:fot=40autox.team.net=22>&lt;fot=40autox.team.net&gt;</a><br clear=3D=
=22none=22 />
<b>Verzonden:</b> Maandag 10 februari 2020 02:34:27<br clear=3D=22none=22=
 />
<b>Onderwerp:</b> =5B=46ot=5D Camshaft recommendation<br clear=3D=22none=22=
 /></div>
<div><br clear=3D=22none=22 /></div>
<div>Hi all, I=E2=80=99m building a TR6 race engine and have a set of 1.6=
5 ratio roller rockers from Goodparts. Any recommendations for a suitable=
 camshaft=3F I will be putting in cam bearings.&=23160;
<div><br clear=3D=22none=22 />
<div>Thanks, Mike<br clear=3D=22none=22 />
<br clear=3D=22none=22 />
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<pre class=3D=22moz-quote-pre=22 wrap=3D=22=22>=5F=5F=5F=5F=5F=5F=5F=5F=5F=
=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=5F=
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--===============4806931183855281534==--

---

From: "van.mulders.marcel--- via Fot" <[email-masked]>
Date: Fri, 21 Feb 2020 01:51:21 +0100 (CET)

--===============7122860105182510016==
	boundary="=_1891b40c-20b7-4252-b1c4-b2dfca9c12df"

--=_1891b40c-20b7-4252-b1c4-b2dfca9c12df
Content-Transfer-Encoding: quoted-printable

Larry, you say most camshafts smack the lifters hard. Will a smaller valve =
clearance relieve this a bit? Has it disadvantages to set the clearance sma=
ller than recommended?(except that the valves will run hotter)=20
Marcel=20

Van: "fot" <[email-masked]>=20
Aan: "fot" <[email-masked]>=20
Verzonden: Woensdag 19 februari 2020 22:14:38=20
Onderwerp: Re: [Fot] Camshaft recommendation=20

I agree with much of what Richard says. The problem with the TR6 engine is =
it has a tiny 0.8" diameter lifter, so as Richard says the higher ratio roc=
ker can help to overcome this limitation. As you mention, one wants a quick=
 opening (and closing). That means high acceleration. Remember Newton's law=
 F =3D ma? What most people don't realize is that the rocker ratio's effect=
 on the forces is squared: (1.65/1.5)^2 =3D 1.21. So the valves and valve s=
prings are effectively 20% heavier. Ideally, to do it properly you would de=
velop a grind for the specific rocker ratio. That being said, from measurin=
g a number of after market cams, I've found most are not particularly aggre=
ssive in terms of the acceleration, but many smack the lifter hard initiall=
y and slam the valve back down on the seat (high ramp velocity), which can =
cause valve bounce and other problems. You can find a bit more discussion a=
t my website - [ http://tildentechnologies.com/Cams/CamSprings.html | http:=
//tildentechnologies.com/Cams/CamSprings.html ] .=20

Another point. I think people get hung up on valve lift. After all, the val=
ve is at maximum lift for an infinitesimal time. I suggest you look at the =
duration the valve is open at intermediate lifts of say 0.20. To avoid losi=
ng the low end, you want to do this without excessively large seat-to-seat =
duration. For a given seat-to-seat (or 0.050) duration, there is no downsid=
e to more lift, since it usually produces more duration at intermediate lif=
ts.=20
Cheers,=20
Larry Young=20

On 2/12/2020 12:19 PM, van.mulders.marcel--- via Fot wrote:=20

Richard,=20

Van: "Richard Good" [ mailto:[email-masked] | <[email-masked]=
Aan: "van mulders marcel" [ mailto:[email-masked] | <van.mul=
[email-masked]> ]=20
Cc: "fot" [ mailto:[email-masked] | <[email-masked]> ]=20
Verzonden: Woensdag 12 februari 2020 17:25:10=20
Onderwerp: Re: [Fot] Camshaft recommendation=20

Marcel,=20

Richard=20

On Wednesday, February 12, 2020 van.mulders.marcel < [ mailto:van.mulders.m=
[email-masked] | [email-masked] ] > wrote:=20

Van: "Richard Good" [ mailto:[email-masked] | <[email-masked]=
> ] )=20
Aan: "Michael Zbarsky" [ mailto:[email-masked] | <[email-masked]> ]=
 , [ mailto:[email-masked] | [email-masked] ] , "van muld=
ers marcel" [ mailto:[email-masked] | <van.mulders.marcel@te=
lenet.be> ]=20

Cc: "fot" [ mailto:[email-masked] | <[email-masked]> ]=20
Verzonden: Woensdag 12 februari 2020 02:23:07=20
Onderwerp: Re: [Fot] Camshaft recommendation=20
7.887=20

Michael,=20

Richard Good=20
Good Parts Inc=20

Sent from AOL Mobile Mail=20
Get the new AOL app: mail.mobile.aol.com=20
On Tuesday, February 11, 2020 Michael Zbarsky via Fot < [ mailto:mzbarsky@y=
ahoo.com | [email-masked] ] > wrote:=20
Thanks everyone! Good stuff. I=E2=80=99m sticking to a redline of just over=
 6K. I=E2=80=99d also like to keep the 1.65 setup rather than invest in a 1=
.55 so keep the intel and suggestions coming. The GP3 is a definite contend=
er.=20

Mike=20

On Monday, February 10, 2020, 4:07 PM, Geoff Byrne [ mailto:gkbyrne@optusne=
t.com.au | <[email-masked]> ] wrote:=20
BQ_BEGIN

Sent from my iPhone=20

BQ_BEGIN
On 11 Feb 2020, at 12:52 am, van.mulders.marcel--- via Fot [ mailto:fot@aut=
ox.team.net | <[email-masked]> ] wrote:=20

BQ_BEGIN

Van: "fot" [ mailto:[email-masked] | <[email-masked]> ]=20
Aan: "fot" [ mailto:[email-masked] | <[email-masked]> ]=20
Verzonden: Maandag 10 februari 2020 02:34:27=20
Onderwerp: [Fot] Camshaft recommendation=20

Thanks, Mike=20

 ]=20
Archive: [ http://autox.team.net/archive | http://autox.team.net/archive ] =
[ http://www.team.net/pipermail/fot | http://www.team.net/pipermail/fot ]=
=20
[email-masked] | http://autox.team.net/mailman/options/fot/van.mulders.=
[email-masked] ]=20

 ]=20
Archive: [ http://autox.team.net/archive | http://autox.team.net/archive ] =
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=20

ushome.com.au | http://autox.team.net/mailman/options/fot/gkbyrne@optushome=
.com.au ]=20

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Archive: [ http://autox.team.net/archive | http://autox.team.net/archive
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Content-Transfer-Encoding: quoted-printable

<html><body><div style=3D"font-family: Verdana, Arial, Helvetica, sans-seri=
f; font-size: 10pt; color: #000000"><div><br></div><div>Larry, you say most=
 camshafts smack the lifters hard. Will a smaller valve clearance relieve t=
his a bit? Has it disadvantages to set the clearance smaller than recommend=
ed?(except that the valves will run hotter)</div><div>Marcel</div><hr id=3D=
"zwchr" data-marker=3D"__DIVIDER__"><div data-marker=3D"__HEADERS__"><b>Van=
: </b>"fot" &lt;[email-masked]&gt;<br><b>Aan: </b>"fot" &lt;[email-masked]=
eam.net&gt;<br><b>Verzonden: </b>Woensdag 19 februari 2020 22:14:38<br><b>O=
nderwerp: </b>Re: [Fot] Camshaft recommendation<br></div><div><br></div><di=
v data-marker=3D"__QUOTED_TEXT__">I agree with much of what Richard says. T=
he problem with the TR6
    engine is it has a tiny 0.8" diameter lifter, so as Richard says the
    higher ratio rocker can help to overcome this limitation. As you
    mention, one wants a quick opening (and closing). That means high
    acceleration. Remember Newton's law F =3D ma? What most people don't
    realize is that the rocker ratio's effect on the forces is squared:
    (1.65/1.5)^2 =3D 1.21. So the valves and valve springs are effectively
    20% heavier. Ideally, to do it properly you would develop a grind
    for the specific rocker ratio. That being said, from measuring a
    number of after market cams, I've found most are not particularly
    aggressive in terms of the acceleration, but many smack the lifter
    hard initially and slam the valve back down on the seat (high ramp
    velocity), which can cause valve bounce and other problems. You can
    find a bit more discussion at my website -
    <a href=3D"http://tildentechnologies.com/Cams/CamSprings.html" target=
=3D"_blank" rel=3D"nofollow noopener noreferrer">http://tildentechnologies.=
com/Cams/CamSprings.html</a>.<br>
    <br>
    Another point. I think people get hung up on valve lift. After all,
    the valve is at maximum lift for an infinitesimal time. I suggest
    you look at the duration the valve is open at intermediate lifts of
    say 0.20. To avoid losing the low end, you want to do this without
    excessively large seat-to-seat duration. For a given seat-to-seat
    (or 0.050) duration, there is no downside to more lift, since it
    usually produces more duration at intermediate lifts.<br>
    Cheers,<br>
    Larry Young<br>
    <br>
    <div class=3D"moz-cite-prefix">On 2/12/2020 12:19 PM,
      van.mulders.marcel--- via Fot wrote:<br>
    </div>
    <blockquote>
     =20
      <div style=3D"font-family:'verdana' , 'arial' , 'helvetica' , sans-se=
rif;font-size:10pt;color:#000000">
        <div><br>
        </div>
        <div>Richard,</div>
        <div>dare I answer again...</div>
        <div>You say :" first decide what will be the optimum lift for
          your engine , then... ": in that case : what is the point of
          high ratio rocker arms, if you want to end at the same maximum
          valve lift? With a higher lobe x lower rocker ratio, the valve
          opening speed will be the same and you have a lower force
          (load) at the pushrods and lobe/cam followers. I think the
          only reason for a higher rocker ratio is the camfollowers
          having a too small a diameter to be able to get at the maximum
          valve lift you want?</div>
        <div>Marcel</div>
        <hr id=3D"zwchr">
        <div><b>Van: </b>"Richard Good"
          <a href=3D"mailto:[email-masked]" target=3D"_blank" rel=3D=
"nofollow noopener noreferrer">&lt;[email-masked]&gt;</a><br>
          <b>Aan: </b>"van mulders marcel"
          <a href=3D"mailto:[email-masked]" target=3D"_blank=
" rel=3D"nofollow noopener noreferrer">&lt;[email-masked]&gt=
;</a><br>
          <b>Cc: </b>"fot" <a href=3D"mailto:[email-masked]" target=3D"=
_blank" rel=3D"nofollow noopener noreferrer">&lt;[email-masked]&gt;</a>=
<br>
          <b>Verzonden: </b>Woensdag 12 februari 2020 17:25:10<br>
          <b>Onderwerp: </b>Re: [Fot] Camshaft recommendation<br>
        </div>
        <div><br>
        </div>
        <div>
          <p dir=3D"ltr">Marcel,</p>
          <p dir=3D"ltr">Yes, if you increase rocker ratio and do not
            change the cam lift, the maximum lift will also increase by
            13%.</p>
          <p dir=3D"ltr">Richard</p>
          <p dir=3D"ltr">Sent from AOL Mobile Mail <br>
            Get the new AOL app: mail.mobile.aol.com</p>
          <hr style=3D"border:0;height:1px;color:#999;background-color:#999=
;width:100%;margin:0 0 9px 0;padding:0"><span style=3D"font-size:14px;color=
:#999999">On Wednesday, February
            12, 2020 van.mulders.marcel &lt;<span style=3D"color:#0000a0"><=
a href=3D"mailto:[email-masked]" target=3D"_blank" rel=3D"no=
follow noopener noreferrer">[email-masked]</a></span>&gt;
            wrote:</span><br>
          <div>
            <div style=3D"font-family:'verdana' , 'arial' , 'helvetica' , s=
ans-serif;font-size:10pt;color:#000000">
              <div>Richard,&nbsp;</div>
              <div>dare I answer this...</div>
              <div>Do you mean that, with the higher rocker ratio, the
                valve is moving faster in the first part of the opening
                phase and hence moving slower nearing the maximum lift?
                Suppose the cam lift of both camshafts is such that the
                maximum lift is 13mm for both the 1.65 and 1.50 ratio
                and duration at 0.050" is 240=C2=B0, thus the crank has to
                move 120=C2=B0 to go from 0.050" lift to maximum lift in bo=
th
                cases. If the valve is opening 13% faster all the way
                from 0.050" lift untill maximum lift, the maximum lift
                will also be 13% higher! When an engine is at, say
                5000rpm or any other speed, it takes the same time to
                move 120=C2=B0 (from 0.050" to maximum lift) : the rocker a=
rm
                ratio does not change that and the valve that is opening
                13% faster with the 1.65 ratio will end at a maximum
                lift that is also 13% higher.&nbsp;</div>
              <div>Marcel</div>
              <hr id=3D"yiv9741220511zwchr">
              <div><b>Van: </b>"Richard Good"
                <a href=3D"mailto:[email-masked]" target=3D"_blank" =
rel=3D"nofollow noopener noreferrer">&lt;[email-masked]&gt;</a>)<br =
clear=3D"none">
                <b>Aan: </b>"Michael Zbarsky"
                <a href=3D"mailto:[email-masked]" target=3D"_blank" rel=
=3D"nofollow noopener noreferrer">&lt;[email-masked]&gt;</a>, <a href=
=3D"mailto:[email-masked]" target=3D"_blank" rel=3D"nofollow noope=
ner noreferrer">[email-masked]</a>,
                "van mulders marcel"
                <a href=3D"mailto:[email-masked]" target=3D"=
_blank" rel=3D"nofollow noopener noreferrer">&lt;van.mulders.marcel@telenet=
.be&gt;</a>
                <div class=3D"yiv9741220511yqt0090589858" id=3D"yiv97412205=
11yqtfd74605"><br clear=3D"none">
                  <b>Cc: </b>"fot" <a href=3D"mailto:[email-masked]" ta=
rget=3D"_blank" rel=3D"nofollow noopener noreferrer">&lt;[email-masked]=
&gt;</a><br clear=3D"none">
                  <b>Verzonden: </b>Woensdag 12 februari 2020 02:23:07<br c=
lear=3D"none">
                  <b>Onderwerp: </b>Re: [Fot] Camshaft recommendation<br cl=
ear=3D"none">
                </div>
              </div>
              <div class=3D"yiv9741220511yqt0090589858" id=3D"yiv9741220511=
yqtfd30775">
                <div>&nbsp;7.887</div>
                <div>
                  <p dir=3D"ltr">Michael,</p>
                  <p dir=3D"ltr">People often seem to overlook the main
                    performance benefit of increasing the rocker ratio.&nbs=
p;
                    That is the increase in valve velocity.&nbsp; The
                    velocity of a flat tappet is limited by it's
                    diameter. If you grind the cam lobe for too much
                    velocity the contact patch will move out past the
                    edge of the lifter and things will self destruct.&nbsp;
                    So tappet velocity is limited.&nbsp; However, since
                    tappet velocity times rocker ratio equals valve
                    velocity, increasing the rocker ratio will increase
                    valve velocity.</p>
                  <p dir=3D"ltr">First decide what will be the optimum
                    valve lift for your engine then divide by rocker
                    ratio to determine the net cam lift needed to
                    achieve that valve lift.&nbsp; Yes, you can grind the c=
am
                    with a large enough lobe to reach desired lift using
                    stock rockers but you are limited in how fast you
                    can open the valve.&nbsp; Now if you grind the cam with
                    less lift then use 1.65:1 rockers to reach that same
                    desired valve lift you will be moving the valve
                    about 13% faster. That means it will be open further
                    in a given period of time.&nbsp; Graph it out and you
                    will see a big difference.&nbsp; Valve velocity is a hu=
ge
                    factor in performance.&nbsp; </p>
                  <p dir=3D"ltr">I can understand why someone who has
                    tried to use high ratio rockers with a cam that was
                    already maxing out the valve lift with stock rockers
                    would decide that high ratio does not work.&nbsp; Valve
                    lift was already at max. Increasing it further may
                    be a detriment.&nbsp; If duration was also maxed out fo=
r
                    reasonable torque then the increase in lift during
                    the overlap period caused by the increase in rocker
                    ratio may reduce the low end torque.&nbsp; Properly
                    applied with the right cam profile, high ratio
                    rockers enable performance that is just not
                    achievable with stock rockers.</p>
                  <p dir=3D"ltr">Richard Good<br clear=3D"none">
                    Good Parts Inc</p>
                  <p dir=3D"ltr">Sent from AOL Mobile Mail <br clear=3D"non=
e">
                    Get the new AOL app: mail.mobile.aol.com</p>
                  <hr style=3D"border:0;min-height:1px;color:#999;backgroun=
d-color:#999;width:100%;margin:0 0 9px 0;padding:0"><span style=3D"font-siz=
e:14px;color:#999999">On Tuesday,
                    February 11, 2020 Michael Zbarsky via Fot &lt;<span sty=
le=3D"color:#0000a0"><a href=3D"mailto:[email-masked]" target=3D"_blank=
" rel=3D"nofollow noopener noreferrer">[email-masked]</a></span>&gt;
                    wrote:</span><br clear=3D"none">
                  <div>
                    Thanks everyone! Good stuff. I=E2=80=99m sticking to a
                    redline of just over&nbsp;6K. I=E2=80=99d also like to =
keep the
                    1.65 setup rather than invest in a 1.55 so keep the
                    intel and&nbsp;suggestions coming. The GP3 is a definit=
e
                    contender.&nbsp;
                    <div><br clear=3D"none">
                    </div>
                    <div>Mike&nbsp;<br clear=3D"none">
                      <br clear=3D"none">
                      <br clear=3D"none">
                      <br clear=3D"none">
                      <div class=3D"yiv9741220511yqt2182859488" id=3D"yiv97=
41220511yqt21880">
                        <p class=3D"yiv9741220511yahoo-quoted-begin" style=
=3D"font-size:15px;color:#715ffa;padding-top:15px;margin-top:0">On
                          Monday, February 10, 2020, 4:07 PM, Geoff
                          Byrne <a href=3D"mailto:[email-masked]" =
target=3D"_blank" rel=3D"nofollow noopener noreferrer">&lt;gkbyrne@optusnet=
.com.au&gt;</a> wrote:</p>
                        <blockquote class=3D"yiv9741220511iosymail">
                          <div id=3D"yiv9741220511">
                            <div>Ditch the 1.65 rockers no good for
                              racing
                              <div>Geoff Byrne</div>
                              <div>TR6 racer down under<br clear=3D"none">
                                <br clear=3D"none">
                                <div dir=3D"ltr">Sent from my iPhone</div>
                                <div dir=3D"ltr"><br clear=3D"none">
                                  <blockquote>On 11 Feb 2020, at 12:52
                                    am, van.mulders.marcel--- via Fot
                                    <a href=3D"mailto:[email-masked]" t=
arget=3D"_blank" rel=3D"nofollow noopener noreferrer">&lt;[email-masked]=
t&gt;</a> wrote:<br clear=3D"none">
                                    <br clear=3D"none">
                                  </blockquote>
                                </div>
                                <blockquote>
                                  <div dir=3D"ltr">
                                    <div style=3D"font-family:'verdana' , '=
arial' , 'helvetica' , sans-serif;font-size:10pt;color:#000000">
                                      <div>I also once bought a
                                        Goodparts 1.65 rocker roller
                                        assembly for a TR6 engine, but
                                        in the end I had to use a 1.55
                                        roller rocker assembly, also
                                        from Goodparts, because, with
                                        the 1.65, it is difficult to
                                        find a race camshaft with a&nbsp;
                                        lobe lift that is low enough.
                                        With lobes of 8mm or higher, I
                                        could not find valve springs to
                                        cope with the high valve lift. I
                                        bought a G5 camshaft from
                                        Schneider, they call it&nbsp; the
                                        320-F grind (duration is 268=C2=B0 =
at
                                        0.050", timing is 57-83&nbsp; &nbsp=
; 87-53
                                        , installation figure is then
                                        103=C2=B0 :is that the same as the =
G5
                                        grind?) with 0.340"/8.6mm cam
                                        lift and that makes for a&nbsp; val=
ve
                                        lift of 12.9mm with the 1.55
                                        rocker arms. With 1.65 rockers ,
                                        valve lift would be 14.2mm and I
                                        could not find valve springs for
                                        that lift. The valve springs I
                                        used are part no 281003-063.20
                                        from Summit (Isky), 320lb/inch
                                        spring rate. They recommend
                                        0.45"/11.43mm&nbsp; (1.250" -
                                        0.800"from closed to full open
                                        position, so it is about 1.4mm
                                        more in my engine, but there is
                                        no problem concerning&nbsp; coil
                                        binding : the installed height
                                        is a 1mm more than 1.250 , the
                                        pressure in closed position is
                                        lower&nbsp; of course, but still
                                        34kgs (105kgs at full lift) an
                                        that seems to be enough till
                                        7500 rpm</div>
                                      <div>Racetorations have a race cam
                                        with 7.6mm cam lift, probably
                                        that would work with 1.65 rocker
                                        arms. I still have the 1.65
                                        rocker assembly, it is new and
                                        it could work with a road cam or
                                        any camshaft with a maximum of
                                        8mm cam lift.</div>
                                      <div>Marcel</div>
                                      <div><br clear=3D"none">
                                      </div>
                                      <hr id=3D"yiv9741220511zwchr">
                                      <div><b>Van: </b>"fot"
                                        <a href=3D"mailto:[email-masked]=
t" target=3D"_blank" rel=3D"nofollow noopener noreferrer">&lt;[email-masked]=
m.net&gt;</a><br clear=3D"none">
                                        <b>Aan: </b>"fot"
                                        <a href=3D"mailto:[email-masked]=
t" target=3D"_blank" rel=3D"nofollow noopener noreferrer">&lt;[email-masked]=
m.net&gt;</a><br clear=3D"none">
                                        <b>Verzonden: </b>Maandag 10
                                        februari 2020 02:34:27<br clear=3D"=
none">
                                        <b>Onderwerp: </b>[Fot]
                                        Camshaft recommendation<br clear=3D=
"none">
                                      </div>
                                      <div><br clear=3D"none">
                                      </div>
                                      <div>
                                        Hi all, I=E2=80=99m building a TR6 =
race
                                        engine and have a set of 1.65
                                        ratio roller rockers from
                                        Goodparts. Any recommendations
                                        for a suitable camshaft? I will
                                        be putting in cam bearings.&nbsp;
                                        <div><br clear=3D"none">
                                          <div>Thanks, Mike<br clear=3D"non=
e">
                                            <br clear=3D"none">
                                            <br clear=3D"none">
                                          </div>
                                        </div>
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From: Larry Young via Fot <[email-masked]>
Date: Fri, 21 Feb 2020 10:13:55 -0600

This is a multi-part message in MIME format.
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Yes, the down side to a smaller clearance is that the seat-to-seat 
duration and valve overlap will increase causing a loss of the low end. 
This page > http://tildentechnologies.com/Cams/Tip_Lash.html shows a 
case where the duration would increase about 32 degrees to about 4x86 = 
344 degrees. I like to call this the "tuning fork effect" it sets of all 
kinds of vibrations which can cause the valve to jump off the lifter and 
bounce off the seat at closing.

I did not intend to imply most smack the lifter, just that many do. This 
is a good reason to thoroughly measure your cam profile. Most stuff on 
the web talks about valve springs as the only cure for valve float issues.
  - Larry

On 2/20/2020 6:51 PM, [email-masked] wrote:
>
> Larry, you say most camshafts smack the lifters hard. Will a smaller 
> valve clearance relieve this a bit? Has it disadvantages to set the 
> clearance smaller than recommended?(except that the valves will run 
> hotter)
> Marcel

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  <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
  </head>
  <body text="#000000" bgcolor="#FFFFFF">
    Yes, the down side to a smaller clearance is that the seat-to-seat
    duration and valve overlap will increase causing a loss of the low
    end. This page &gt; <a class="moz-txt-link-freetext" href="http://tildentechnologies.com/Cams/Tip_Lash.html">http://tildentechnologies.com/Cams/Tip_Lash.html</a>
    shows a case where the duration would increase about 32 degrees to
    about 4x86 = 344 degrees. I like to call this the "tuning fork
    effect" it sets of all kinds of vibrations which can cause the valve
    to jump off the lifter and bounce off the seat at closing. <br>
    <br>
    I did not intend to imply most smack the lifter, just that many do.
    This is a good reason to thoroughly measure your cam profile. Most
    stuff on the web talks about valve springs as the only cure for
    valve float issues.<br>
     - Larry<br>
    <br>
    <div class="moz-cite-prefix">On 2/20/2020 6:51 PM,
      <a class="moz-txt-link-abbreviated" href="mailto:[email-masked]">[email-masked]</a> wrote:<br>
    </div>
    <blockquote type="cite"
      cite="mid:[email-masked]">
      <meta http-equiv="content-type" content="text/html; charset=UTF-8">
      <div style="font-family: Verdana, Arial, Helvetica, sans-serif;
        font-size: 10pt; color: #000000">
        <div><br>
        </div>
        <div>Larry, you say most camshafts smack the lifters hard. Will
          a smaller valve clearance relieve this a bit? Has it
          disadvantages to set the clearance smaller than
          recommended?(except that the valves will run hotter)</div>
        <div>Marcel<br>
        </div>
      </div>
    </blockquote>
    <br>
  </body>
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From: Enquiries Road & Track via Fot <[email-masked]>
Date: Sat, 22 Feb 2020 19:28:49 +1000

--===============2916813410751343870==

--000000000000ec7f62059f26bb0d

it seems most of the better cam grinders these days have some very fancy
software for examining the motion of the valve for any cam/valve train
being proposed. They can easily calculate the critical acceleration and
deceleration limits for any valve train mass and its not hard to 'plot" the
motion of the cam/valve lifter, even if they did not create the actual cam
being studied.   Ive done this on my lathe with a data capture system,. Ive
just finished a major exercise with one cam maker on my Toyota 4AG race
engine where I suspected valve train harmonics were responsible for a
broken cam (actually snapped in 2 at peak rpm) . valve spring makers  like
PAC in the USA are known to have such software.

it seems like many TR cam profiles were created in the ancient past,
possibly more by trial an error than serious maths. Thats not to say they
are wrong/bad, but rather there is a more modern alternative that might
have a place. Some cam makers may be using such approaches with TR cams,
but I suspect many are just churning out what they did 30 years ago. .

Terry O'Beirne

On Sat, Feb 22, 2020 at 2:14 AM Larry Young via Fot <[email-masked]>
wrote:

> This page > http://tildentechnologies.com/Cams/Tip_Lash.html shows a case
> where the duration would increase about 32 degrees to about 4x86 = 344
> degrees. I like to call this the "tuning fork effect" it sets of all kinds
> of vibrations which can cause the valve to jump off the lifter and bounce
> off the seat at closing.
>
> is a good reason to thoroughly measure your cam profile. Most stuff on the
> web talks about valve springs as the only cure for valve float issues.
>  - Larry
>
> Larry, you say most camshafts smack the lifters hard. Will a smaller valve
> clearance relieve this a bit? Has it disadvantages to set the clearance
> smaller than recommended?(except that the valves will run hotter)
> Marcel
>
>
> Unsubscribe/Manage <http://www.team.net/pipermail/fotUnsubscribe/Manage>:
> http://autox.team.net/mailman/options/fot/[email-masked]
>
>
>

--000000000000ec7f62059f26bb0d
Content-Transfer-Encoding: quoted-printable

<div dir=3D"ltr">it seems most of the better cam grinders these days have s=
ome very fancy software for examining the motion of the valve for any cam/v=
alve train being proposed. They can easily calculate=C2=A0the critical acce=
leration and deceleration limits for any valve train mass and its not hard =
to &#39;plot&quot; the motion of the cam/valve lifter, even if they did not=
 create the actual cam being studied.=C2=A0 =C2=A0Ive done this on my lathe=
 with a data capture system,. Ive just=C2=A0finished a major exercise with =
one cam maker on my Toyota 4AG race engine where I suspected valve train ha=
rmonics=C2=A0were responsible for a broken cam (actually snapped in 2 at pe=
ak rpm) . valve spring makers=C2=A0 like PAC in the USA are known to have s=
uch software.<div><br></div><div>it seems=C2=A0like many TR cam=C2=A0profil=
es were created in the ancient=C2=A0past, possibly more by trial an error=
=C2=A0than serious maths. Thats not to say they are wrong/bad, but rather t=
here is a more modern alternative that might have a place. Some cam makers =
may be using such approaches with TR cams, but I suspect many are just chur=
ning out what they did 30 years ago. .=C2=A0=C2=A0<br><div><br></div><div><=
div><div dir=3D"ltr" data-smartmail=3D"gmail_signature"><div dir=3D"ltr"><d=
iv><div dir=3D"ltr"><div><div dir=3D"ltr"><div><div dir=3D"ltr"><div><div d=
ir=3D"ltr"><div><div dir=3D"ltr"><div>Terry O&#39;Beirne</div></div></div><=
/div></div></div></div></div></div></div></div></div></div></div><br></div>=
</div></div><br><div class=3D"gmail_quote"><div dir=3D"ltr" class=3D"gmail_=
attr">On Sat, Feb 22, 2020 at 2:14 AM Larry Young via Fot &lt;<a href=3D"ma=
ilto:[email-masked]" target=3D"_blank">[email-masked]</a>&gt; wrote=
:<br></div><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.=
8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
 =20
   =20
 =20
  <div bgcolor=3D"#FFFFFF">
    Yes, the down side to a smaller clearance is that the seat-to-seat
    duration and valve overlap will increase causing a loss of the low
    end. This page &gt; <a href=3D"http://tildentechnologies.com/Cams/Tip_L=
ash.html" target=3D"_blank">http://tildentechnologies.com/Cams/Tip_Lash.htm=
l</a>
    shows a case where the duration would increase about 32 degrees to
    about 4x86 =3D 344 degrees. I like to call this the &quot;tuning fork
    effect&quot; it sets of all kinds of vibrations which can cause the val=
ve
    to jump off the lifter and bounce off the seat at closing. <br>
    <br>
    I did not intend to imply most smack the lifter, just that many do.
    This is a good reason to thoroughly measure your cam profile. Most
    stuff on the web talks about valve springs as the only cure for
    valve float issues.<br>
    =C2=A0- Larry<br>
    <br>
    <div>On 2/20/2020 6:51 PM,
      <a href=3D"mailto:[email-masked]" target=3D"_blank">va=
[email-masked]</a> wrote:<br>
    </div>
    <blockquote type=3D"cite">
     =20
      <div style=3D"font-family:Verdana,Arial,Helvetica,sans-serif;font-siz=
e:10pt;color:rgb(0,0,0)">
        <div><br>
        </div>
        <div>Larry, you say most camshafts smack the lifters hard. Will
          a smaller valve clearance relieve this a bit? Has it
          disadvantages to set the clearance smaller than
          recommended?(except that the valves will run hotter)</div>
        <div>Marcel<br>
        </div>
      </div>
    </blockquote>
    <br>
  </div>

_______________________________________________<br>
<a href=3D"mailto:[email-masked]" target=3D"_blank">[email-masked]<=
/a><br>
<br>
<a href=3D"http://www.fot-racing.com" rel=3D"noreferrer" target=3D"_blank">=
http://www.fot-racing.com</a><br>
<br>
et=3D"_blank">http://www.team.net/donate.html</a><br>
Archive: <a href=3D"http://autox.team.net/archive" rel=3D"noreferrer" targe=
t=3D"_blank">http://autox.team.net/archive</a> <a href=3D"http://www.team.n=
et/pipermail/fotUnsubscribe/Manage" rel=3D"noreferrer" target=3D"_blank">ht=
tp://www.team.net/pipermail/fot<br>
t/[email-masked]" rel=3D"noreferrer" target=3D"_blank">http:=
//autox.team.net/mailman/options/fot/[email-masked]</a><br>
<br>
<br>
</blockquote></div>

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---

From: Larry Young via Fot <[email-masked]>
Date: Sat, 22 Feb 2020 10:17:18 -0600

This is a multi-part message in MIME format.
--===============0572638041600162803==
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"it seems most of the better cam grinders these days have some very 
fancy software".  -  That has not been my experience for TR cams, maybe 
for SBC cams. - Larry

On 2/22/2020 3:28 AM, Enquiries Road & Track wrote:
> it seems most of the better cam grinders these days have some very 
> fancy software for examining the motion of the valve for any cam/valve 
> train being proposed. They can easily calculate the critical 
> acceleration and deceleration limits for any valve train mass and its 
> not hard to 'plot" the motion of the cam/valve lifter, even if they 
> did not create the actual cam being studied.   Ive done this on my 
> lathe with a data capture system,. Ive just finished a major exercise 
> with one cam maker on my Toyota 4AG race engine where I suspected 
> valve train harmonics were responsible for a broken cam (actually 
> snapped in 2 at peak rpm) . valve spring makers  like PAC in the USA 
> are known to have such software.
>
> possibly more by trial an error than serious maths. Thats not to say 
> they are wrong/bad, but rather there is a more modern alternative that 
> might have a place. Some cam makers may be using such approaches with 
> TR cams, but I suspect many are just churning out what they did 30 
> years ago. .
>
> Terry O'Beirne
>
>
> On Sat, Feb 22, 2020 at 2:14 AM Larry Young via Fot 
>
>     end. This page > http://tildentechnologies.com/Cams/Tip_Lash.html
>     effect" it sets of all kinds of vibrations which can cause the
>     valve to jump off the lifter and bounce off the seat at closing.
>
>     I did not intend to imply most smack the lifter, just that many
>     do. This is a good reason to thoroughly measure your cam profile.
>     Most stuff on the web talks about valve springs as the only cure
>     for valve float issues.
>      - Larry
>
>     On 2/20/2020 6:51 PM, [email-masked]
>>
>>     Larry, you say most camshafts smack the lifters hard. Will a
>>     smaller valve clearance relieve this a bit? Has it disadvantages
>>     to set the clearance smaller than recommended?(except that the
>>     valves will run hotter)
>>     Marcel
>
>     Unsubscribe/Manage
>     <http://www.team.net/pipermail/fotUnsubscribe/Manage>:

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<html>
  <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
  </head>
  <body text="#000000" bgcolor="#FFFFFF">
    "it seems most of the better cam grinders these days have some very
    fancy software".  -  That has not been my experience for TR cams,
    maybe for SBC cams. - Larry<br>
    <br>
    <div class="moz-cite-prefix">On 2/22/2020 3:28 AM, Enquiries Road
      &amp; Track wrote:<br>
    </div>
    <blockquote type="cite"
cite="mid:CA+UW8b2GeLKbF+ndrY-U0p8Q1pv_LvpP=[email-masked]">
      <meta http-equiv="content-type" content="text/html; charset=UTF-8">
      <div dir="ltr">it seems most of the better cam grinders these days
        have some very fancy software for examining the motion of the
        valve for any cam/valve train being proposed. They can easily
        calculate the critical acceleration and deceleration limits for
        any valve train mass and its not hard to 'plot" the motion of
        the cam/valve lifter, even if they did not create the actual cam
        being studied.   Ive done this on my lathe with a data capture
        system,. Ive just finished a major exercise with one cam maker
        on my Toyota 4AG race engine where I suspected valve train
        harmonics were responsible for a broken cam (actually snapped in
        2 at peak rpm) . valve spring makers  like PAC in the USA are
        known to have such software.
        <div><br>
        </div>
        <div>it seems like many TR cam profiles were created in the
          ancient past, possibly more by trial an error than serious
          maths. Thats not to say they are wrong/bad, but rather there
          is a more modern alternative that might have a place. Some cam
          makers may be using such approaches with TR cams, but I
          suspect many are just churning out what they did 30 years ago.
          .  <br>
          <div><br>
          </div>
          <div>
            <div>
              <div dir="ltr" data-smartmail="gmail_signature">
                <div dir="ltr">
                  <div>
                    <div dir="ltr">
                      <div>
                        <div dir="ltr">
                          <div>
                            <div dir="ltr">
                              <div>
                                <div dir="ltr">
                                  <div>
                                    <div dir="ltr">
                                      <div>Terry O'Beirne</div>
                                    </div>
                                  </div>
                                </div>
                              </div>
                            </div>
                          </div>
                        </div>
                      </div>
                    </div>
                  </div>
                </div>
              </div>
            </div>
            <br>
          </div>
        </div>
      </div>
      <br>
      <div class="gmail_quote">
        <div dir="ltr" class="gmail_attr">On Sat, Feb 22, 2020 at 2:14
          AM Larry Young via Fot &lt;<a href="mailto:[email-masked]"
            target="_blank" moz-do-not-send="true">[email-masked]</a>&gt;
          wrote:<br>
        </div>
        <blockquote class="gmail_quote" style="margin:0px 0px 0px
          0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
          <div bgcolor="#FFFFFF"> Yes, the down side to a smaller
            clearance is that the seat-to-seat duration and valve
            overlap will increase causing a loss of the low end. This
            page &gt; <a
              href="http://tildentechnologies.com/Cams/Tip_Lash.html"
              target="_blank" moz-do-not-send="true">http://tildentechnologies.com/Cams/Tip_Lash.html</a>
            shows a case where the duration would increase about 32
            degrees to about 4x86 = 344 degrees. I like to call this the
            "tuning fork effect" it sets of all kinds of vibrations
            which can cause the valve to jump off the lifter and bounce
            off the seat at closing. <br>
            <br>
            I did not intend to imply most smack the lifter, just that
            many do. This is a good reason to thoroughly measure your
            cam profile. Most stuff on the web talks about valve springs
            as the only cure for valve float issues.<br>
             - Larry<br>
            <br>
            <div>On 2/20/2020 6:51 PM, <a
                href="mailto:[email-masked]"
                target="_blank" moz-do-not-send="true">[email-masked]</a>
              wrote:<br>
            </div>
            <blockquote type="cite">
              <div
style="font-family:Verdana,Arial,Helvetica,sans-serif;font-size:10pt;color:rgb(0,0,0)">
                <div><br>
                </div>
                <div>Larry, you say most camshafts smack the lifters
                  hard. Will a smaller valve clearance relieve this a
                  bit? Has it disadvantages to set the clearance smaller
                  than recommended?(except that the valves will run
                  hotter)</div>
                <div>Marcel<br>
                </div>
              </div>
            </blockquote>
            <br>
          </div>
          _______________________________________________<br>
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