[Fot] Camshaft recommendation

[vfracing at aol.com]

We played around with rocker ratios on a computer simulation of a TR4 engine.  The added lift increased max HP by about 3 HP peak.  Low end (under about 3500 rpm) torque was actually reduced a very small amount.  If the TR6 results were similar, probably not worth the hassle of added valve spring issues and reduced valve guide length (greater valve guide wear).
For what it's worth....
Phil


-----Original Message-----
From: van.mulders.marcel--- via Fot <fot at autox.team.net>
To: Michael Zbarsky <mzbarsky at yahoo.com>
Cc: fot <fot at autox.team.net>
Sent: Mon, Feb 10, 2020 8:52 am
Subject: Re: [Fot] Camshaft recommendation

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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