I stand correcting......... for any given camshaft, the average valve velocity
will change with a rocker ratio change. For example, if changing the rocker
ratio increases valve lift to say 16mm instead of 13mm, then the average
velocity increase is 16/13 or 12%. this is because the lift occurs in the same
time (cam/crank moves the same amount).
What I really should have said originally, is, the biggest useful influence
over the rate of valve opening, is the camshaft, because flow testing suggests
you need a big increase in rate of lift early in the cycle, not just averaged.
I will take some measurements of cam rates on various Triumph cams and report
back.
To the various folk who emailed me about lifters, I understand various sized
lifters can be fitted---its just a case of boring out the 12 lifter bores
(tedious job). Cam grinders will specify the minimum cam follower diameter
their cam will successfuly work on. The faster the acceleration rate of the
cam, the larger the lifter diameter required. If you dont get the lifter
diamter correct, the cam will edge ride. This means the lower edge of the
lifter will try to dig into the cam, rather than ride up and over it.
I would be deligthed to ehar form anyone who has such cam data, or even what is
the most agreeive cam people have found to work on stock lifters.
Terry O'Beirne
_______________________________________________
http://www.team.net/donate.html
Fot mailing list
Fot@autox.team.net
http://autox.team.net/mailman/listinfo/fot
|