Quote:

Do the math. Hes nowhere near 10.5 to 1. Lucky if its 9.5 to 1.
Probably 2 points down from the 383.







I did the math as you suggested.

With slightly shaved 906,s you can expect 88 cc chamber volume or higher.

using.

87cc chamber
4.36 bore
4.50 gasket bore
4cc valve reliefs
.015 in the hole
.039 gasket ========= 9.75 comp.

With only a slight shave on the 906,s the Comp,s probably even less then that. More like 9.5


There are no measurements to estimate the 383,s true comp. I based my opinion on the stated 11.2 and 10.5 comp difference.

The 906,s chamber would need to be around 79cc or less to hit the 10.5 comp mark.