Hi can someone shed some light on what may expect for a comp. ratio with this setup
72 350, #7 heads(64CC w W-31 Valve size), Flat top Speedpro's 30 over, .040 felpro head gaskets. No other block/head mods

THANKS

 

Based on the numbers you provided and assuming the pistons are sitting .010 down, about 10.6.

http://www.csgnetwork.com/compcalc.html

 

The 10.5 is what the factory rated the W-31 motor in its day with steel shim gaskets(.017).
But the Felpros are .040. i was thinking in the 9.5 range with the thicker gaskets???

 

The numbers don't lie. You will be way higher 9.5. Your engine is also bored, so that effects it a little too.

I'm not up on the older Olds as others, so I'll let them chime in on the W-31 specifics, but understand the factory advertised 'numbers' are based on perfect blueprint specs, NOT reality. For example, the factory rated CR assumes a perfect blueprint 64 cc head and a piston to deck clearance of 0. Reality has your heads more around 68 cc's and the pistons sitting .025 down. That will make your CR alot lower than one may think.

 

I did a big write up on this back when I was at OP. YOU GOTTA MEASURE EVERYTHING! Too many variables. FWIW, every SpeePro piston I used was down .024 +/- with no decking. Again, align hone, decking, milling, gaskets, head work and rod re-sizing all affect the Cr.

 

Unless you measure your actual parts, mathematical gymnastics are just speculation. You cannot get accurate CR info from guesswork inputs, right?