Ignition timing

340mopar said
I must be missing something, the longer duration the cam the lower your compression number needs to be? So if I run 12:1 with a 255 @.050 duration it will run better with a 9:1 compression?

Or do you mean the longer the duration the cam the lower your cylinder pressure will be at cranking so you need more advance?

You must mean the latter because the cam will not change the compression ratio.

What I meant to say is a engine with a long duration cam will need more intial timing to idle acceptably. And/or, an engine with low compression will need more intital timing idle acceptably.