How Much Can Heads Improve Compression???

Ok: here are some of the specs:

Piston drop is .087" down - flat top I can get pictures later.

Volume above piston at TDC: 17 cc


Bore = 3.91 in
Stroke = 3.31 in

Swept Volume: 651.29 cc

"Kit" head gasket volume = 12.4 cc

360 head volume Casting # 3671587 = 69 cc

Clearance Volume with 360 heads = 98.4
Compression with 360 heads = 7.62