Subject: Re: [Fot] Camshaft recommendation

From: Richard Good via Fot <[email-masked]>
Date: Tue, 18 Feb 2020 05:02:23 +0000 (UTC)

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Marcel,

If you were to reduce the tappet velocity of the lower lift cam by 13% as w=
ell as reducing the cam lift then there would be no point.=C2=A0 But if you=
 grind the lower lift cam with the same lifter velocity as the high lift ca=
m then the high ratio rockers will give you 13% higher valve speed than the=
 high lift cam with stock rockers.

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,dare I answer again...You say :" first decide what will be the opti=
mum lift for your engine , then... ": in that case : what is the point of h=
igh ratio rocker arms, if you want to end at the same maximum valve lift? W=
ith 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 follow=
ers. 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 y=
ou want?MarcelVan: "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 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
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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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<p dir=3D"ltr">Marcel,</p>
<p dir=3D"ltr">If you were to reduce the tappet velocity of the lower lift =
cam by 13% as well as reducing the cam lift then there would be no point.&#=
160; But if you grind the lower lift cam with the same lifter velocity as t=
he high lift cam then the high ratio rockers will give you 13% higher valve=
 speed than the high lift cam with stock rockers.</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<br><br></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"yiv0854756989"><html><div><div style=3D"font-family:Verdana, Arial, He=
lvetica, sans-serif;font-size:10pt;color:#000000;"><div><br clear=3D"none">=
</div><div>Richard,</div><div>dare I answer again...</div><div>You say :&qu=
ot; first decide what will be the optimum lift for your engine , then... &q=
uot;: in that case : what is the point of high ratio rocker arms, if you wa=
nt 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"yiv0854756989zwchr"><div class=3D"yiv0854756989yqt1550548151" id=
=3D"yiv0854756989yqt35507"><div><b>Van: </b>&quot;Richard Good&quot; &lt;go=
[email-masked]&gt;<br clear=3D"none"><b>Aan: </b>&quot;van mulders mar=
cel&quot; &lt;[email-masked]&gt;<br clear=3D"none"><b>Cc: </=
b>&quot;fot&quot; &lt;[email-masked]&gt;<br clear=3D"none"><b>Verzonden=
: </b>Woensdag 12 februari 2020 17:25:10<br clear=3D"none"><b>Onderwerp: </=
b>Re: [Fot] Camshaft recommendation<br clear=3D"none"></div><div><br clear=
=3D"none"></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 clear=3D"none">
Get the new AOL app: mail.mobile.aol.com</p>
<div class=3D"yiv0854756989device_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 =
Wednesday, February 12, 2020 van.mulders.marcel &lt;<span style=3D"color:#0=
000a0;">[email-masked]</span>&gt; wrote:</span><br clear=3D"=
none"><div id=3D"yiv0854756989"></div><div><div style=3D"font-family:'verda=
na' , 'arial' , 'helvetica' , sans-serif;font-size:10pt;color:#000000;"><di=
v>Richard,=C2=A0</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 par=
t of the opening phase and hence moving slower nearing the maximum lift? Su=
ppose 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% highe=
r! 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 change that and the valve that is opening 13% faster with th=
e 1.65 ratio will end at a maximum lift that is also 13% higher.=C2=A0</div=
><div>Marcel</div><hr id=3D"yiv0854756989zwchr"><div><b>Van: </b>&quot;Rich=
ard Good&quot; &lt;[email-masked]&gt;)<br clear=3D"none"><b>Aan: </b=
>&quot;Michael Zbarsky&quot; &lt;[email-masked]&gt;, [email-masked]=
om.au, &quot;van mulders marcel&quot; &lt;[email-masked]&gt;=
<div class=3D"yiv0854756989yqt0090589858" id=3D"yiv0854756989yqtfd74605"><b=
r clear=3D"none"><b>Cc: </b>&quot;fot&quot; &lt;[email-masked]&gt;<br c=
lear=3D"none"><b>Verzonden: </b>Woensdag 12 februari 2020 02:23:07<br clear=
=3D"none"><b>Onderwerp: </b>Re: [Fot] Camshaft recommendation<br clear=3D"n=
one"></div></div><div class=3D"yiv0854756989yqt0090589858" id=3D"yiv0854756=
989yqtfd30775"><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"yiv0854756989device_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"yiv0854756989"></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"yiv0854756989yqt2182859488" id=3D"yiv0854756989yqt21880"><p class=3D"=
yiv0854756989yahoo-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"yiv08547=
56989iosymail"><div id=3D"yiv0854756989"><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"yiv0854756989zwchr"><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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--===============2230411086445592967==--

---

From: "van.mulders.marcel--- via Fot" <[email-masked]>
Date: Tue, 18 Feb 2020 09:22:25 +0100 (CET)

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Richard,=20
I agree (after reading it 3 times to understand it).=20
The possibility of speeding up the tappet velocity is limited though : it i=
s this problem that cam grinders encounter when they try to get very fast v=
alve opening. It's common agreed that very fast valve opening (steep flank)=
 with less overlap is an advantage, but there are limits.=20
Marcel=20

Van: "Richard Good" <[email-masked]>=20
Aan: "van mulders marcel" <[email-masked]>=20
Cc: "fot" <[email-masked]>=20
Verzonden: Dinsdag 18 februari 2020 06:02:23=20
Onderwerp: Re: [Fot] Camshaft recommendation=20

Marcel,=20

If you were to reduce the tappet velocity of the lower lift cam by 13% as w=
ell as reducing the cam lift then there would be no point. But if you grind=
 the lower lift cam with the same lifter velocity as the high lift cam then=
 the high ratio rockers will give you 13% higher valve speed than the high =
lift cam with stock rockers.=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 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

--=_0e5e4368-283e-4567-88ce-c9ed095f3a39
Content-Transfer-Encoding: quoted-printable

<html><body><div style=3D"font-family: Verdana, Arial, Helvetica, sans-seri=
f; font-size: 10pt; color: #000000"><div>Richard,&nbsp;</div><div>I agree (=
after reading it 3 times to understand it).</div><div>The possibility of sp=
eeding up the tappet velocity is limited though : it is this problem that c=
am grinders encounter when they try to get very fast valve opening. It's co=
mmon agreed that very fast valve opening (steep flank) with less overlap is=
 an advantage, but there are limits.</div><div>Marcel</div><div><br></div><=
hr id=3D"zwchr" data-marker=3D"__DIVIDER__"><div data-marker=3D"__HEADERS__=
"><b>Van: </b>"Richard Good" &lt;[email-masked]&gt;<br><b>Aan: </b>"=
van mulders marcel" &lt;[email-masked]&gt;<br><b>Cc: </b>"fo=
t" &lt;[email-masked]&gt;<br><b>Verzonden: </b>Dinsdag 18 februari 2020=
 06:02:23<br><b>Onderwerp: </b>Re: [Fot] Camshaft recommendation<br></div><=
div><br></div><div data-marker=3D"__QUOTED_TEXT__"><p dir=3D"ltr">Marcel,</=
p>
<p dir=3D"ltr">If you were to reduce the tappet velocity of the lower lift =
cam by 13% as well as reducing the cam lift then there would be no point.&n=
bsp; But if you grind the lower lift cam with the same lifter velocity as t=
he high lift cam then the high ratio rockers will give you 13% higher valve=
 speed than the high lift cam with stock rockers.</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<br><br></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"yiv0854756989"></div=
><div><div style=3D"font-family:'verdana' , 'arial' , 'helvetica' , sans-se=
rif;font-size:10pt;color:#000000"><div><br clear=3D"none"></div><div>Richar=
d,</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 i=
s the point of high ratio rocker arms, if you want to end at the same maxim=
um valve lift? With a higher lobe x lower rocker ratio, the valve opening s=
peed 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 t=
he camfollowers having a too small a diameter to be able to get at the maxi=
mum valve lift you want?</div><div>Marcel</div><hr id=3D"yiv0854756989zwchr=
"><div class=3D"yiv0854756989yqt1550548151" id=3D"yiv0854756989yqt35507"><d=
iv><b>Van: </b>"Richard Good" &lt;[email-masked]&gt;<br clear=3D"non=
e"><b>Aan: </b>"van mulders marcel" &lt;[email-masked]&gt;<b=
r clear=3D"none"><b>Cc: </b>"fot" &lt;[email-masked]&gt;<br clear=3D"no=
ne"><b>Verzonden: </b>Woensdag 12 februari 2020 17:25:10<br clear=3D"none">=
<b>Onderwerp: </b>Re: [Fot] Camshaft recommendation<br clear=3D"none"></div=
><div><br clear=3D"none"></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 clear=3D"none">
Get the new AOL app: mail.mobile.aol.com</p>
<div class=3D"yiv0854756989device_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 We=
dnesday, February 12, 2020 van.mulders.marcel &lt;<span style=3D"color:#000=
0a0">[email-masked]</span>&gt; wrote:</span><br clear=3D"non=
e"><div id=3D"yiv0854756989"></div><div><div style=3D"font-family:'verdana'=
 , 'arial' , 'helvetica' , sans-serif;font-size:10pt;color:#000000"><div>Ri=
chard,&nbsp;</div><div>dare I answer this...</div><div>Do you mean that, wi=
th 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? Suppos=
e 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 both =
cases. If the valve is opening 13% faster all the way from 0.050" lift unti=
ll maximum lift, the maximum lift will also be 13% higher! When an engine i=
s 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 th=
at 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"yiv0854756989zwchr"><div><b>Van: </b>"Richard Good" &lt;goodparts@veriz=
on.net&gt;)<br clear=3D"none"><b>Aan: </b>"Michael Zbarsky" &lt;mzbarsky@ya=
hoo.com&gt;, [email-masked], "van mulders marcel" &lt;van.mulders.=
[email-masked]&gt;<div class=3D"yiv0854756989yqt0090589858" id=3D"yiv085=
4756989yqtfd74605"><br clear=3D"none"><b>Cc: </b>"fot" &lt;[email-masked]=
et&gt;<br clear=3D"none"><b>Verzonden: </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 class=3D"yiv0854756989yqt0090589858" id=3D=
"yiv0854756989yqtfd30775"><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 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"yiv0854756989device_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"yiv0854756989"></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"yiv0854756989yqt2182859488" id=3D"yiv0854756989yqt21880"><p class=3D"=
yiv0854756989yahoo-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"yiv085475=
6989iosymail"><div id=3D"yiv0854756989"><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"yiv085475698=
9zwchr"><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"yiv0854756989yqt5723059911" id=3D"yiv0854756989yqtfd7074=
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"yiv0854756989yqt2182859488" id=3D"yiv0854756989yqt54816=
"></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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eferrer" shape=3D"rect" href=3D"http://www.team.net/pipermail/fot" target=
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ribe/Manage: <a rel=3D"nofollow nofollow noopener noreferrer" shape=3D"rect=
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target=3D"_blank">http://autox.team.net/mailman/options/fot/goodparts@veriz=
on.net</a><br clear=3D"none"><br clear=3D"none"><br clear=3D"none"><br clea=
r=3D"none"></div></div></div></div><br clear=3D"none"></div></div></div></d=
iv><br></div></div></body></html>
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