just put a set of 305 vortecs on my 84 z28 alot better throttle response and gas milage my question is before compression guage read about 130 after it read 160psi what is compression ratio and can you figure it out just by the gauge it has stock pistons with the vortec heads 58cc chambers

 

You can't figure it out from the gauge. Too many factors influence that, not the least of which is the condition of the valve job, which went from old and tired to brand-new.

If you took off a set of the stock 305 heads, 416 casting, then your static compression is pretty much unchanged. The chamber size is the same on both types of heads.



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"So many Mustangs, so little time..."
ICON Motorsports

 

rday,

Where did you get Vortecs with 58 cc chambers? Did you have them milled from 64 cc? How much were they?

Thanks,

Matt

 

i got them off ebay for about 300 dollarsthey are out of a 96 chevy pickup no they wernt milled

 

Well if your heads were originally 64 cc combustion chambers, and had 9.5 to 1 compression then shrinking them to 58 cc my educated guess would be ABOUT 10 to 1.