GREAT Thanks - Yep, I forgot my Chevelle by the Numbers books had those, all except the cam duration numbers ... where'd did you get those? Three thngs I Can't make sense of:
First I don't have compression numbers for '70 Head #3964290 Which is what I have). The '69 3931063 compression is spec'd at 10.25:1 in my chevy manual from GM. I don't have GMs 1970 Chevelle book - Can you tell Me?
Second - You say the duration numbers are 350 and 352 - how does that compare to duration numbers reported by new manufacturers like Edelbrock, when they reprot duration on their "Performer RPM Cams" of 240 and 246 degrees at .050 inch (whichh I undertsand is distance from base circle) the two sets of duration numbers don't compare, but I suspect the Edelbrock is more cam, but the duration reported is less than the stock numbers you quote. Isn't the Edelbrock cam more cam? -
Third - Paul Herd in his book Chevelle SS Restoration Guide 1992, MPI Pub. on page 15, says 1970-1972 "All heads were redesigned in 70 to operate on Low Octane fuel ... and now used an open chamber design. ..." ..."... the base L34 engine rated at 350 HP ... used .. conventional heads # 3964290." If the heads were redesigned to run on lower octane, I assume the compression numbers were less that '69 head #3931063. But Colvin Says the two heads were virtually the same except for the spark plug seat! Who's right? Herd or Colvin? And are my 3964290 heads yielding less compressionn than than the '69 #3931063 heads? If so how do they make 350 HP like the prior year heads?
Thanks RonDo you Yahoo!?
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