[flipper35]

I was told by my engine guru that the cam determines the idle timing and the cumbustion chamber shape and piston shape determine total advance. Your cars weight/gearing/transmission determine the rate of advance.

For my engine for example it is 22*/34* in by 2800 and a Dart with a Magnum 360 (quench style chambers) and an auto would be something like 22*/36* in at 3600. With my open chamber design, I get detonation at 36*. Same engine, different heads/pistons.