mach1-Brazil

CHI EM 185 on a stock 351 2V would produce what kind of compression rate?

tks Pedro

brenx

I'll take a stab at it.

I'd say about 10:1. The chamber of a CHI head is either 62cc or 64cc. Regardless of being EM 185CC or the 218CC.

With zero deck height/3 cc valve relief in the pistons/1 cc in a valve/around 9cc for the head gasket/with the head at 60cc. <--- Can't remember exact figures. I've got 11.2:1.

Brenden

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davis

Using a 64cc chamber with a 4.100" gasket at .041" compressed thickness with a single 3cc valve relief at true zero deck produces a calculated (rounded off) 10.6:1 compression ratio. Usually, you'll find that the piston is actually a good bit down from zero. At .008" down, the compression ratio drops to 10.4:1 and at .010" down, it drops to 10.35:1 (all compression ratios are rounded). It is definitely not recommended to drop below about .020-.025" or else the quench effect is dramatically reduced and the likelihood of predetonation increases.

:davis:

xdclevo

If you have not decked the block at all, you would have just under 10.00:1. This is assuming the pistons are at 30 or 35 thou under deck height. And davis said, if the pistons are too far from zero deck height, you may have detonation issues.

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