Distributor Advance Curve

When you buy the Mopar Performance upgrade kit or electronic distributor they tell you “it has a performance advance curve” but they do not give you the specs. I’ve been looking for this advance curve information for a long time and finally came across some useful information that should apply to most Mopar distributors 50’s-70’s if not all as the design seems the same. See page three of the attached Summit Racing instruction page.

I found the hemi likes 28-29 degrees of total advance, and the advance is all in by 3000 RPM. If you set 10 degrees initial timing you need 18-19 degrees in the mechanical advance. The problem is that new distributors might have more advance than that and you won’t know because they don’t give you the specifications. If you put more advance in a hemi at high RPM you risk detonation. A new distributor with no information on the advance curve is mayhem.

For reference, here is a link to distributors used on Letter Cars, specs and advance curves.

John Grady
May, 2020