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Re: [Fot] Camshaft recommendation

To: fot@autox.team.net
Subject: Re: [Fot] Camshaft recommendation
From: Duncan Charlton via Fot <fot@autox.team.net>
Date: Wed, 19 Feb 2020 17:43:44 -0600
Delivered-to: mharc@autox.team.net
Delivered-to: fot@autox.team.net
References: <1417642395.1418618.1581524710564.ref@mail.yahoo.com> <1417642395.1418618.1581524710564@mail.yahoo.com> <1392309332.69004004.1581531598578.JavaMail.zimbra@telenet.be> <e27a821e-8782-06de-e8e3-a8965854cba1@pobox.com>
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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=
 maximum lift will also increase by 13%.
> > Richard
> > Sent from AOL Mobile Mail
> > Get the new AOL app: mail.mobile.aol.com
> > 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>
> > Verzonden: Woensdag 12 februari 2020 02:23:07
> > 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.
> > Richard Good
> > Good Parts Inc
> > Sent from AOL Mobile Mail
> > Get the new AOL app: mail.mobile.aol.com
> > 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:
> > > Ditch the 1.65 rockers no good for racing
> > > Geoff Byrne
> > > TR6 racer down under
> > >
> > > Sent from my iPhone
> > >
> > > > 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>
> > > > Verzonden: Maandag 10 februari 2020 02:34:27
> > > > 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=

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<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 />
<br clear=3D=22none=22 /></div>
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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=5F=5F=
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