Compression...

Well I am running 10.6:1 on a 360 with magnum heads and a comp XE268H cam, my cranking pressure is 175-185 psi.

Because of the excellent quench provided by the zero deck pistons, closed chmaber magnum heads and .039 compressed head gasket this engine runs with no audible detonation on 89 octane.

I am also running 15 degrees intial timing and 34 total (again because of the excellent chamber design less total timing is required) and it's all in at 2500 rpm.