Quote:
Originally Posted by Synchro909
The advance built into these distributors is set for a standard engine with a standard head. We know that as compression rises, less advance is needed.
Does anybody have an idea on how much less advance is needed for a 5.5:1 head? Same question for other after market heads that are available all the way up to about 8 or 9 to 1.
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I've found advance stays the same,1 degree per 100 rpm with a 7 to 1 head,which is the upper limit for a model a head due to flow reduction. There were some problems noted by some people with the FSI advancing a little too far at peak,a few degrees over the 1 per 100 threshold..I don't find that with mine.What does happen when increasing compression is that the engines tolerance for timing deviation lessens,dont run a high compression head with manual advance. 4.2 to 1 is tolerant of timing flaw,you can set one fixed timing and drive..7 to 1 will hammer on you,with a bigger hammer than 4.2 to 1..