--===============8142134401152494555==
boundary="----=_Part_1245557_1844612259.1581470587871"
------=_Part_1245557_1844612259.1581470587871
Content-Transfer-Encoding: quoted-printable
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 <mzbarsky@yahoo.com> =
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 <gkbyrne@optusnet.com.au=
> 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 <fot@autox.team.=
net> wrote:
=EF=BB=BFI also once bought a Goodparts 1.65 rocker roller assembly for a T=
R6 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 cams=
haft 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-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 valve springs for that lift. The valve springs I used are part no 281=
003-063.20 from Summit (Isky), 320lb/inch spring rate. They recommend 0.45"=
/11.43mm=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 coi=
l 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 till 7500 rpmRacetorations have a race cam=
with 7.6mm cam lift, probably that would work with 1.65 rocker arms. I sti=
ll have the 1.65 rocker assembly, it is new and it could work with a road c=
am or any camshaft with a maximum of 8mm cam lift.Marcel
Van: "fot" <fot@autox.team.net>
Aan: "fot" <fot@autox.team.net>
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
_______________________________________________
fot@autox.team.net
http://www.fot-racing.com
Archive: http://autox.team.net/archive http://www.team.net/pipermail/fot
arcel@telenet.be
_______________________________________________
fot@autox.team.net
http://www.fot-racing.com
Archive: http://autox.team.net/archive http://www.team.net/pipermail/fot
home.com.au
_______________________________________________
fot@autox.team.net
http://www.fot-racing.com
Archive: http://autox.team.net/archive http://www.team.net/pipermail/fot
izon.net
------=_Part_1245557_1844612259.1581470587871
Content-Transfer-Encoding: quoted-printable
<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>
</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 Tue=
sday, February 11, 2020 Michael Zbarsky via Fot <<span style=3D"color:#=
0000A0">mzbarsky@yahoo.com</span>> wrote:</span><br></br><div id=3D"yiv=
6930218573"><html><head></head><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"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 By=
rne <gkbyrne@optusnet.com.au> wrote:</p><blockquote class=3D"yiv69302=
18573iosymail"><div id=3D"yiv6930218573"><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 type=3D"cite">On 11 Feb 2020, at 12:52=
am, van.mulders.marcel--- via Fot <fot@autox.team.net> wrote:<br cle=
ar=3D"none"><br clear=3D"none"></blockquote></div><blockquote type=3D"cite"=
><div dir=3D"ltr">=EF=BB=BF<div style=3D"font-family:Verdana, Arial, Helvet=
ica, sans-serif;font-size:10pt;color:#000000;"><div>I also once bought a Go=
odparts 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 th=
e 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, t=
hey call it=C2=A0 the 320-F grind (duration is 268=C2=B0 at 0.050", ti=
ming is 57-83=C2=A0 =C2=A0 87-53 , installation figure is then 103=C2=B0 :i=
s 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 valve springs fo=
r 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=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 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 ro=
ad cam or any camshaft with a maximum of 8mm cam lift.</div><div>Marcel</di=
v><div><br clear=3D"none"></div><hr id=3D"yiv6930218573zwchr"><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>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"no=
ne"></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=
=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"><span>________________________________________=
_______</span><br clear=3D"none"><span>fot@autox.team.net</span><br clear=
=3D"none"><span></span><br clear=3D"none"><span>http://www.fot-racing.com</=
span><br clear=3D"none"><span></span><br clear=3D"none"><span>Donate: http:=
//www.team.net/donate.html</span><br clear=3D"none"><span>Archive: http://a=
utox.team.net/archive http://www.team.net/pipermail/fot</span></div><br cle=
ar=3D"none"><span>Unsubscribe/Manage: http://autox.team.net/mailman/options=
/fot/gkbyrne@optushome.com.au</span><div class=3D"yiv6930218573yqt572305991=
1" id=3D"yiv6930218573yqtfd70749"><br clear=3D"none"><span></span><br clear=
=3D"none"><span></span><br clear=3D"none"></div></div></blockquote></div></=
div></div><blockquote></blockquote></blockquote></div></div>
</div></html></div><html><div class=3D"yqt2182859488" id=3D"yqt54816"><body=
>_______________________________________________<br clear=3D"none"><a shape=
=3D"rect" ymailto=3D"mailto:fot@autox.team.net"; href=3D"mailto:fot@autox.te=
am.net">fot@autox.team.net</a><br clear=3D"none"><br clear=3D"none"><a shap=
e=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 shape=3D=
"rect" href=3D"http://www.team.net/donate.html"; target=3D"_blank">http://ww=
w.team.net/donate.html</a><br clear=3D"none">Archive: <a shape=3D"rect" hre=
f=3D"http://autox.team.net/archive " target=3D"_blank">http://autox.team.ne=
t/archive </a><a shape=3D"rect" href=3D"http://www.team.net/pipermail/fot"; =
target=3D"_blank">http://www.team.net/pipermail/fot</a><br clear=3D"none">U=
nsubscribe/Manage: <a shape=3D"rect" href=3D"http://autox.team.net/mailman/=
options/fot/goodparts@verizon.net" target=3D"_blank">http://autox.team.net/=
mailman/options/fot/goodparts@verizon.net</a><br clear=3D"none"><br clear=
=3D"none"><br clear=3D"none"></body></div></html>
------=_Part_1245557_1844612259.1581470587871--
--===============8142134401152494555==
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
_______________________________________________
fot@autox.team.net
http://www.fot-racing.com
Archive: http://autox.team.net/archive http://www.team.net/pipermail/fot
--===============8142134401152494555==--
|