Quote:


The 915 heads with the original 400 pistons won't get you anywhere near 10-1 compression.



I calculate that if the OP can get the heads down to 72 cc's (and they'll need to be milled for that), run steel shim head gaskets, then assuming the pistons are .100 in the hole at TDC (which is about what the stockers run), the compression ratio would only be 9 to one.

At 78 cc's, the CR would only be 8.6 to one.

At 90 cc's, you're looking at 7.8 to one.

Put some thick Fel-Pro 1009 head gaskets on it instead of steel shims, and knock another 2-3 tenths off any of the above figures.