Timing

I have not been able to "use" the vacuum advance as designed on any non stock motors. I personally set my total advance on a sbm at 34* max and around 20 initial. I have pluged in a scanner on several "modern" engines and monitored the spark advance. I have yet to see one exceed 34*. I believe the "vacuum" advance was more of a emissions/bandaid for factory stock old lady driving that any millage/performance useage. THIS IS JUST MY OPINION/EXPERIANCE.

and I suck at spelling too.