Are you running a regular HEI distributor, or someone's aftermarket design? Most stock distributors require some pretty radical work to the centrifugal advance system to get the right amount of initial advance without over-advancing the centrifugal. I usually reduce the centrifugal advance by about 10 degrees by shortening the length of the slots they move in, and adding the same amount to the initial advance. I like 12 degrees of initial, 24 degrees of centrifugal, maxing out at 2800-3000 RPM, and 10 degrees of vacuum for a total advance of 46 degrees at 3,000 RPM with no load.
Jerry
