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thanks Richard
some folks might like to read this link
https://www.tildentechnologies.com/Cams/TriumphCams.html
I disagree with your comment about grinding stock cams. You cannot always
get the lift desired as in some cases, you would end up grinding below the
core of shaft. Again, this was a real common problem with early 2000 & 2500
cams , which is whey they were often welded on the nose as part of the
modification process. In later production, the factory used a larger
diameter core , presumably to aid stiffness, but that gives a bit more
flexibility when regrinding.
You correctly point out that as you increase the lifter diameter then the
peak velocity can also change. if you run the maths, a change of 0.100"
in lifter diameter (a lot really) gives a 10% increase in acceptable peak
velocity. Changing the lifter diameter is not for the feint-hearted,
especially in a 6 cylinder where the lifter bores are angled to the block
to promote lifter rotation.
It would be good if Geoff Byrne elaborates a bit on his comment
Terry O'Beirne
Road and Track
enquiries@roadandtrack.net.au
ph 0428 815 117
On Wed, Feb 12, 2020 at 11:23 AM Richard Good via Fot <fot@autox.team.net>
wrote:
> Michael,
>
> People often seem to overlook the main performance benefit of 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 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. So tappet velocity is limited.
> However, since tappet velocity times rocker ratio equals valve velocity,
> increasing the rocker ratio will increase valve velocity.
>
> 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 th=
at
> 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 moving the valv=
e
> about 13% faster. 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 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. Valve lift was already at max.
> Increasing it further may be a detriment. 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.
> 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
> 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 ov=
er 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 contender.
>
> Mike
>
>
>
> On Monday, February 10, 2020, 4:07 PM, Geoff Byrne <
> gkbyrne@optusnet.com.au> wrote:
>
> Ditch the 1.65 rockers no good for racing
> Geoff Byrne
> TR6 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=BF
> 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 lobe lift that is low enough. With lobes of 8mm or highe=
r,
> 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 grind (duration is 26=
8=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 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 (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 lowe=
r
> of course, but still 34kgs (105kgs at full lift) an that seems to be enou=
gh
> 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 maximum of 8=
mm
> 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 rat=
io roller
> rockers from Goodparts. Any recommendations for a suitable camshaft? I wi=
ll
> be putting in cam bearings.
>
> Thanks, Mike
>
>
>
> _______________________________________________
> fot@autox.team.net
>
> http://www.fot-racing.com
>
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>
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>
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<div dir=3D"ltr">thanks Richard<div><br></div><div></div><div>some folks mi=
ght like to read this link=C2=A0
<a href=3D"https://www.tildentechnologies.com/Cams/TriumphCams.html";>https:=
//www.tildentechnologies.com/Cams/TriumphCams.html</a>=C2=A0<br></div><div>=
<br></div><div>=C2=A0 I disagree=C2=A0with your comment about grinding stoc=
k cams. You cannot always get the lift desired as in some cases, you would =
end up grinding below the core of shaft. Again, this was a real common prob=
lem with early 2000 & 2500 cams , which is whey they were often welded =
on the nose as part of the modification process. In later production, the f=
actory used a larger diameter=C2=A0core , presumably to aid stiffness, but =
that gives a bit more flexibility when regrinding.=C2=A0=C2=A0<br></div><di=
v><br></div><div>You correctly point out that as you increase the lifter di=
ameter then the peak velocity can also change. if you run the maths, a=C2=
=A0 change of 0.100"=C2=A0 in lifter diameter=C2=A0(a lot really) give=
s a 10% increase in acceptable peak velocity. Changing the lifter diameter=
=C2=A0is not for the feint-hearted, especially in a 6 cylinder where the li=
fter bores are angled to the block to promote lifter rotation.=C2=A0</div><=
div><br></div><div>It would be good if Geoff Byrne elaborates a bit on his =
comment</div><div><br></div><div>Terry O'Beirne</div><div><br></div><di=
v></div><div><br></div><div>=C2=A0 =C2=A0<br></div><div><br></div><div>=C2=
=A0<br></div><div>=C2=A0<br clear=3D"all"><div><div dir=3D"ltr" class=3D"gm=
ail_signature" data-smartmail=3D"gmail_signature"><div dir=3D"ltr"><div><di=
v dir=3D"ltr"><div><div dir=3D"ltr"><div><div dir=3D"ltr"><div><div dir=3D"=
ltr"><div><div dir=3D"ltr"><div>Road and Track</div><div><a href=3D"mailto:=
enquiries@roadandtrack.net.au" target=3D"_blank">enquiries@roadandtrack.net=
.au</a><br>ph 0428 815 117<br><br></div></div></div></div></div></div></div=
></div></div></div></div></div></div></div><br></div></div><br><div class=
=3D"gmail_quote"><div dir=3D"ltr" class=3D"gmail_attr">On Wed, Feb 12, 2020=
at 11:23 AM Richard Good via Fot <<a href=3D"mailto:fot@autox.team.net"=
>fot@autox.team.net</a>> wrote:<br></div><blockquote class=3D"gmail_quot=
e" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204)=
;padding-left:1ex"><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'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>
Good Parts Inc</p>
<p dir=3D"ltr">Sent from AOL Mobile Mail <br>
Get the new AOL app: <a href=3D"http://mail.mobile.aol.com"; target=3D"_blan=
k">mail.mobile.aol.com</a></p>
<div></div><hr style=3D"border:0px;height:1px;color:rgb(153,153,153);backgr=
ound-color:rgb(153,153,153);width:100%;margin:0px 0px 9px;padding:0px"><spa=
n style=3D"font-size:14px;color:rgb(153,153,153)">On Tuesday, February 11, =
2020 Michael Zbarsky via Fot <<span style=3D"color:rgb(0,0,160)"><a href=
=3D"mailto:mzbarsky@yahoo.com"; target=3D"_blank">mzbarsky@yahoo.com</a></sp=
an>> wrote:</span><br><div id=3D"gmail-m_3617476403406723811yiv693021857=
3"><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 id=
=3D"gmail-m_3617476403406723811yiv6930218573yqt21880"><p style=3D"font-size=
:15px;color:rgb(113,95,250);padding-top:15px;margin-top:0px">On Monday, Feb=
ruary 10, 2020, 4:07 PM, Geoff Byrne <<a href=3D"mailto:gkbyrne@optusnet=
.com.au" target=3D"_blank">gkbyrne@optusnet.com.au</a>> wrote:</p><block=
quote><div id=3D"gmail-m_3617476403406723811yiv6930218573"><div>Ditch the 1=
.65 rockers no good for racing<div>Geoff Byrne</div><div>TR6 racer down und=
er<br clear=3D"none"><br clear=3D"none"><div dir=3D"ltr">Sent from my iPhon=
e</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 <<a href=3D"mailto:=
fot@autox.team.net" target=3D"_blank">fot@autox.team.net</a>> wrote:<br =
clear=3D"none"><br clear=3D"none"></blockquote></div><blockquote type=3D"ci=
te"><div dir=3D"ltr">=EF=BB=BF<div style=3D"font-family:Verdana,Arial,Helve=
tica,sans-serif;font-size:10pt;color:rgb(0,0,0)"><div>I also once bought a =
Goodparts 1.65 rocker roller assembly for a TR6 engine, but in the end I ha=
d 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=C2=A0 lobe lift th=
at is low enough. With lobes of 8mm or higher, I could not find valve sprin=
gs 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 tha=
t 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 281003-063.20 from Summ=
it (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 bin=
ding : the installed height is a 1mm more than 1.250 , the pressure in clos=
ed position is lower=C2=A0 of course, but still 34kgs (105kgs at full lift)=
an that seems to be enough till 7500 rpm</div><div>Racetorations have a ra=
ce 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"gmail-m_3617476403406723811yiv6=
930218573zwchr"><div><b>Van: </b>"fot" <<a href=3D"mailto:fot@=
autox.team.net" target=3D"_blank">fot@autox.team.net</a>><br clear=3D"no=
ne"><b>Aan: </b>"fot" <<a href=3D"mailto:fot@autox.team.net"; t=
arget=3D"_blank">fot@autox.team.net</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"non=
e"></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>
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