Originally Posted by bowtie44s
I have the small block cam retarded 4 degrees, the big block is straight up. I haven't messed with the small block for a while. I am adjusting initial timing. I don't know when the mechanical advance starts but i would assume after 750rpm. I have the vacuum advance unhooked and when i slow the timing much below 60 it starts idling rough and will die.
So it idles w/60 degrees BTDC and then the mechanical advance adds to that? Yikes!!
As long as you've confirmed TDC, firing order, etc. like you have, unless the carb is way out of tune/faulty/"modified", there's no way it should need anywhere near that kind of timing. So I'd start w/the carb:
As long as the carb is working right and not too far from factory specs, I'd start by baselining the transfer slots of whatever carb you're using. Then use initial advance and idle bypass air to get it to idle w/o the primary throttle blades being open too far. This can be done in several ways depending on the carb; a Holley can use the secondary throttle shaft adjustment screw to tip them open a little. If bad enough (although this is rare) holes can be drilled in the primary blades, but that's only as a last resort.