[Fot] Camshaft recommendation

[Michael Zbarsky]

Thanks everyone! Good stuff. I’m sticking to a redline of just over 6K. I’d 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 at 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 at autox.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, 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 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 grind (duration is 268° at 0.050", timing is 57-83    87-53 , installation figure is then 103° :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 lower  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 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.Marcel
Van: "fot" <fot at autox.team.net>
Aan: "fot" <fot at autox.team.net>
Verzonden: Maandag 10 februari 2020 02:34:27
Onderwerp: [Fot] Camshaft recommendation

Hi all, I’m 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. 
Thanks, Mike



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