Played with the timing curve in my streetfire HEI distributor. Switched vacuum advance to ported vacuum. My original setup had 6 degrees of base timing, 12 degrees of vac. advance, & 18 degrees of mechanical advance. I reduced vac. advance to 8 degrees & boosted base timing to 10 degrees. Gives me the same 36 degrees total, all in by 2500 RPM, but is stronger off the line now.