The builder says we should be around 10.3:1 CR with the 75 cc heads. He is more concerned about valve clearance though. So that’s why I was thinking maybe go with the 80cc, and then if we need to have them milled down to where we want, that would be good. Thoughts on that idea?
Also, what about the roller rockers vs stamped steel, or any opinion on the Mancini version of the Harlan rockers? Thanks.
With 75 ccs, I get more like 10.8:1 using a piston deck of 0.006". 80 cc would be 10.3:1. You posted a deck distance of 0.060", but that would be very odd, and would be 9.6:1 w/ 75cc
For what your looking at in cam size, P/V should not be an issue, but you'll need to check. Radially, the valve has a bigger diameter too.
I won't share my opinion on rockers, and be prepared for an exhaustive, repetitive discussion on rocker arm geometery.
