Quote:
Originally Posted by c20pickup
they said the heads were 1978 model year with the hardened seats if that helps any
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1978 wasn't known for high compression heads. And it is possible to build a 9:1 compression motor with advertised 12.5:1 pistons. I Need to know combustion chamber size, thickness of head gasket, camshaft profile, cylinder size and piston dome size/shape to guesstimate compression ratios. A flat top piston with 2 valve reliefs are commonly called 10:1 pistons, but they dont make that compression with every head.
It has happened that some people put 305 heads on a 350 to get better compression, but the valves are shrouded by the small combustion chamber which reduces flow around the valves.
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2005 GMC K2500HD D/A
1993 GMC K1500
2011 Subaru Legacy.
2013 Subaru Outback
1970 C-10 2WD, SWB stepside, 292, TH350, PS, more rust than anything. God is my pilot.
