1965 273 Heads

I had some new duals bent, and attached to the existing exhaust manifolds (which I'd also like to replace with some TTI's)......... that's another story, though.

Tell me what I'm missing - the spec manual says that the 273 Commando (235 HP) had something like 12:1 compression... and that the 273 2bbl only had something like 9:1. That difference doesn't come from the heads? ...... or do I just need to change the valves? .... or what? How would the pistons make that difference?

The spec manual also says that the Commando had a different cam. This, I'm sure, would give the old block a little kick.