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Old 02-16-2006, 04:40 AM
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Compression Calculator

Going strictly by your numbers and build, 9:1 CR is a little much for supreme pump gas. The problem is the .450 total cam lift vs. dynamic compression ratio. The more lift/duration of the cam, the less CR. the engine sees. A real strong cam might have a .750 total lift and corresponding duration along with a 1-1 1/2 point drop in compression ratio. Then at 8-8 1/2 ratio any problems could be offset by "Total Ignition Retard" say from initial setting of 36* to as much as 3* less (33*). Furthe reduction would hurt the power too much in my opinion.

In any case, check the static compression by using a known good pressure guage and fresh battery. Block the throttle wide open, crank the engine about 5 compression strokes. For the street, in no case should the readings exceed 170 pounds (max for premium pump gas).

From what I know, this should give you an engine that will have a reasonably long life and run near or at the peak of it's potential at the same time.

Until you know the engine... read those plugs for metallic flakes or blistering. You know that the best read is to see some color up inside the plug with a little white on the porcelin tip, however that is cutting it very close, perhaps the tan tip is best here.

This subject has nany facets. I strongly suggest that you research and triple check all the info you can... to build a dependable engine!
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