[Stan Weiss]

Originally Posted by Stan Weiss

What the engine wants / needs is a given valve lift curve for your combination of parts. Pontiac put 1.65:1 rockers on the RAIV, because with a .842"diameter flat tappet lifter you can NOT produce a cam lobe that with 1.5:1 rockers can produce that valve lift curve.

Stan

I should not post late at night. I have corrected my post.

The engine would need somewhere around a .940" diameter flat tappet lifter to be able to have a cam lobe that with a 1.5:1 rocker would produce the same valve lift curve as the RAIV with 1.65:1 rockers.

Stan

PS - Many cams are not designed close to the max. This shows the Intake valve lift for a Pontiac 068 cam and Sumit 2801 both with 1.5:1 rockers.