Quote Originally Posted by 1gary View Post
That is 9.4 C/R with RHS#12001 72cc heads and a intake runner of 180cc.
No, here is a copy of what I figured in post #47...
I'd use the 12410 heads. With your 18cc pistons, in the hole 0.010" and a 0.040" gasket, you'll be at 9.4:1 static compression ratio. The 12410's have bronze guides, 64cc chambers, 2.02"/1.60" valves, +0.100" long. I might order the heads bare from Competition Products along with the valves, springs (part number on the timing card linked here), etc. and have Pat put 'em together.

You can use anything you want. I was just trying to follow along. The custom cam I suggested in post #63 works real well with the 9.4, but you won't have 9.4 if you run a different chamber size. Also, I don't like those pistons. The only squish there is....is a thin ring of material above the rings. Ain't gonna be much squish there. Might work ok, but they wouldn't be my choice for a high cylinder pressure motor.