Listers,
My theory is NEVER install a reground cam. The price on regrinds makes them
tempting, but too often they don't hold up. My 71 Vixen 2500 has the Triumph
TR6 engine with the factory S-4 cam, purchased through the competition
department. It was considered to be not a "street" cam, but I find it to be
quite okay for street use. Along with a shaved head to increase compression
ratio, it gives a very nice increase in power. A very healthy sound at idle,
and what little it gives up at engine speeds below 3000rpm it more than makes
up for at revs above 3000! That engine has plenty of torque to begin with
anyway.
I can't remember the specs right now, but I think we are talking about 290
degrees duration, .450" lift at valve, or pretty close to those numbers. For
the street, look for a cam with no more than 292 degrees duration, 296 if you
want to live on the edge. Either way, you must increase compression ratio to
take advantage of the cam. Be careful of the specs on the cam. There are
different ways these numbers are obtained. Some grinders give numbers that
document duration and lift at the cam at .020" lift, others at .050" lift at
the cam. Others give numbers that are measured at the valve. The numbers I
gave are measured at the valve, and will be higher than those measured at the
cam.
Whatever you end up installing, remember that a big factor in how whatever cam
you choose performs, is the break-in period. Coat everything with cam lube,
use high quality, new, lifters, set your clearances with great care, make sure
that all systems are "go", and run the engine at 2000rpm for 20 minutes. This
work hardens the cam lobes, and helps insure that the lobes don't wear down.
This is where reground cams can, and many times do, give it up!
As far as suppliers go, I suggest talking to Richard Good--(Goodparts. com)??
or Ted Schumaker--(TSI Imports.com)?? Maybe "Erson Cams"?? Babe Erson used
to work at Isky cams. There are probably many others. Rimmer or Revington
are possibilities.
Just my 2 cents. Hope it helps.
Rich Rock
Pottstown, PA
64 TR4
65 TR4A-IRS (Isky cam)
67 TR4A...parts
70 TVR Vixen (soon to get 296 degree cam, not reground)
71 TVR Vixen 2500 (S-4 cam)
|