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Re: [Fot] Camshaft recommendation

To: Larry Young <cartravel@pobox.com>
Subject: Re: [Fot] Camshaft recommendation
From: "van.mulders.marcel--- via Fot" <fot@autox.team.net>
Date: Fri, 21 Feb 2020 01:51:21 +0100 (CET)
Cc: fot <fot@autox.team.net>
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>
Thread-index: dclJWhfq9s9ZVDlGla909+ZW6lMVeQ==
Thread-topic: Camshaft recommendation
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Larry, you say most camshafts smack the lifters hard. Will a smaller valve =
clearance relieve this a bit? Has it disadvantages to set the clearance sma=
ller than recommended?(except that the valves will run hotter)=20
Marcel=20

Van: "fot" <fot@autox.team.net>=20
Aan: "fot" <fot@autox.team.net>=20
Verzonden: Woensdag 19 februari 2020 22:14:38=20
Onderwerp: Re: [Fot] Camshaft recommendation=20

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

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

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




Richard,=20
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" [ mailto:goodparts@verizon.net | <goodparts@verizon.net=
> ]=20
Aan: "van mulders marcel" [ mailto:van.mulders.marcel@telenet.be | <van.mul=
ders.marcel@telenet.be> ]=20
Cc: "fot" [ mailto:fot@autox.team.net | <fot@autox.team.net> ]=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 < [ mailto:van.mulders.m=
arcel@telenet.be | van.mulders.marcel@telenet.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" [ mailto:goodparts@verizon.net | <goodparts@verizon.net=
> ] )=20
Aan: "Michael Zbarsky" [ mailto:mzbarsky@yahoo.com | <mzbarsky@yahoo.com> ]=
 , [ mailto:gkbyrne@optusnet.com.au | gkbyrne@optusnet.com.au ] , "van muld=
ers marcel" [ mailto:van.mulders.marcel@telenet.be | <van.mulders.marcel@te=
lenet.be> ]=20

Cc: "fot" [ mailto:fot@autox.team.net | <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 < [ mailto:mzbarsky@y=
ahoo.com | 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 [ mailto:gkbyrne@optusne=
t.com.au | <gkbyrne@optusnet.com.au> ] wrote:=20
BQ_BEGIN

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 [ mailto:fot@aut=
ox.team.net | <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" [ mailto:fot@autox.team.net | <fot@autox.team.net> ]=20
Aan: "fot" [ mailto:fot@autox.team.net | <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
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=20
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marcel@telenet.be ]=20

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.com.au ]=20




BQ_END


BQ_END

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t ]=20





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arcel@telenet.be=20

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