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Does anyone know what the static compression should be with a 84" pan with a B cam? I'm kind of surprised at how low mine is after a fresh re-build (85 lbs) Could my valve timing be an issue? Or should I have gone with high compression pistons? I was not informed by the shop that bored my cylinders and ordered the new S&S stroker pistons if there was more than one option,I seem to be learning the hard way...Mike
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Mike -
The stock 'H' cam has the front intake closing at 46 degs ABDC, and a rear intake closing at 38 degs ABDC. This info comes from the Andrews website. Your 'B' grind has an intake closing at 50 degs ABDC, for both front and rear. A considerable drop in 'effective' compression. This cam is used for major high-domed pistons, and in your case an increase from stock in the stroke of your engine. So, you must have gone with some really low-domed pistons on your build, to get that value (85#) of cranking pressure.
But, to really answer your question, more information is needed. Like bore, stroke, piston dome displacement, head volume chamber displacement (if it has changed). The specs are already known for the cam.
Jack -
Thanks Jack, I'll see if I can dig up some more facts...MikeComment
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Jack, the pistons are S&S 92-2723 I have S&S 4 1/2" stroke wheels with a stock bore, .030 over. I curently have the heads off for intake thread repair, (Headhog). beforehand I checked the compression with the throttle wide open,and I kicked her over three or four comp. strokes and wound up with only 85 lbs. The pushrods spun normally. At this point All I can do is wait for my heads then try it again, I had run the motor thru about twenty start ups in the garage just till the heads felt warm. Thats when I found the intake leaks. I guess what I'm asking is what would normal compression be? Thanks for the time you spend helping guys like me figuring this stuff out, I really appreciate it! MikeComment
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