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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" <goodparts@verizon.net>)=20
Aan: "Michael Zbarsky" <mzbarsky@yahoo.com>, gkbyrne@optusnet.com.au, "van =
mulders marcel" <van.mulders.marcel@telenet.be>=20
Cc: "fot" <fot@autox.team.net>=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 < mzbarsky@yahoo.com =
> 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 <gkbyrne@optusnet.com.au=
> 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
On 11 Feb 2020, at 12:52 am, van.mulders.marcel--- via Fot <fot@autox.team.=
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" <fot@autox.team.net>=20
Aan: "fot" <fot@autox.team.net>=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
fot@autox.team.net=20
http://www.fot-racing.com=20
Archive: http://autox.team.net/archive http://www.team.net/pipermail/fot=20
arcel@telenet.be=20
_______________________________________________=20
fot@autox.team.net=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:fot@autox.team.net | fot@autox.team.net ]=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/goodparts@verizon.ne=
t ]=20
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<html><body><div style=3D"font-family: Verdana, Arial, Helvetica, sans-seri=
f; font-size: 10pt; color: #000000"><div>Richard, </div><div>dare I an=
swer 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 mov=
ing 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 g=
o from 0.050" lift to maximum lift in both cases. If the valve is opening 1=
3% faster all the way from 0.050" lift untill maximum lift, the maximum lif=
t will also be 13% higher! When an engine is at, say 5000rpm or any other s=
peed, 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=
13% faster with the 1.65 ratio will end at a maximum lift that is also 13%=
higher. </div><div>Marcel</div><hr id=3D"zwchr" data-marker=3D"__DIVI=
DER__"><div data-marker=3D"__HEADERS__"><b>Van: </b>"Richard Good" <good=
parts@verizon.net>)<br><b>Aan: </b>"Michael Zbarsky" <mzbarsky@yahoo.=
com>, gkbyrne@optusnet.com.au, "van mulders marcel" <van.mulders.marc=
el@telenet.be><br><b>Cc: </b>"fot" <fot@autox.team.net><br><b>Verz=
onden: </b>Woensdag 12 februari 2020 02:23:07<br><b>Onderwerp: </b>Re: [Fot=
] Camshaft recommendation<br></div><div> 7.887</div><div data-marker=
=3D"__QUOTED_TEXT__"><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. That is the increase in valve velocity=
. 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. So tappet vel=
ocity is limited. 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. 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 m=
oving the valve about 13% faster. That means it will be open further in a g=
iven period of time. Graph it out and you will see a big difference.&=
nbsp; Valve velocity is a huge factor in performance. </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. Valve lift was alr=
eady at max. Increasing it further may be a detriment. 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. 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>
Good Parts Inc</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 Tuesday, February 11,=
2020 Michael Zbarsky via Fot <<span style=3D"color:#0000a0">mzbarsky@ya=
hoo.com</span>> wrote:</span><br><div id=3D"yiv6930218573"></div><div>
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 i=
n a 1.55 so keep the intel and suggestions coming. The GP3 is a defini=
te contender. <div><br clear=3D"none"></div><div>Mike <br clear=
=3D"none"><br clear=3D"none"><br clear=3D"none"><br clear=3D"none"><div cla=
ss=3D"yiv6930218573yqt2182859488" id=3D"yiv6930218573yqt21880"><p class=3D"=
yiv6930218573yahoo-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 <gkbyrne@optusnet.com.au> wrote:</p><blockquote class=3D"yiv693021=
8573iosymail"><div id=3D"yiv6930218573"><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 <fot@autox.team.net> 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 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 g=
rind (duration is 268=C2=B0 at 0.050", 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 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 (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 coil binding : the installed height is a 1mm more than 1.250 , t=
he pressure in closed position is lower 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"yiv693021857=
3zwchr"><div><b>Van: </b>"fot" <fot@autox.team.net><br clear=3D"none"=
><b>Aan: </b>"fot" <fot@autox.team.net><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>
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. <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=
=3D"none">fot@autox.team.net<br clear=3D"none"><br clear=3D"none">http://ww=
w.fot-racing.com<br clear=3D"none"><br clear=3D"none">Donate: http://www.te=
am.net/donate.html<br clear=3D"none">Archive: http://autox.team.net/archive=
http://www.team.net/pipermail/fot<br clear=3D"none">Unsubscribe/Manage: ht=
tp://autox.team.net/mailman/options/fot/van.mulders.marcel@telenet.be<div c=
lass=3D"yiv6930218573yqt5723059911" id=3D"yiv6930218573yqtfd51209"><br clea=
r=3D"none"></div></div></div><div class=3D"yiv6930218573yqt5723059911" id=
=3D"yiv6930218573yqtfd38997">______________________________________________=
_<br clear=3D"none">fot@autox.team.net<br clear=3D"none"><br clear=3D"none"=
>http://www.fot-racing.com<br clear=3D"none"><br clear=3D"none">Donate: htt=
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/gkbyrne@optushome.c=
om.au<div class=3D"yiv6930218573yqt5723059911" id=3D"yiv6930218573yqtfd7074=
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"yqt2182859488" id=3D"yqt54816"></div>__________________=
_____________________________<br clear=3D"none"><a shape=3D"rect" href=3D"m=
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