11 to 1 on pump gas

My 360 has 10.6:1 static compression and cranks 195-205 psi and runs fine on 89 octane. I have tried 87 but I need to be careful. even on 100+ degree days it runs fine on 89.

The key to this high compression on iron heads is a tight quench. The magnum heads I am using ate closed chamber and the pistons are at zero deck, with the .039 thick head gasket I have an
Ideal quench that makes the engine very detonation resistant.

Note: good cylinder turbulence requires less timing. I run 33 with it all in at 2500 rpm. Initial timing is 17.