Working out compression ratio

EvilGus67

Newbie
Hi,
I need to find an approximate compression ratio for my 401 Nailhead. Its bored 60 over, so I can calculate the increase in swept volume making the cylinder volume 15.4609 cubic inches.

If I knew the volume of the cylinder head combustion chamber and the thickness of a standard gasket I could approximate a compression ratio.

Can anyone tell me what the combustion chamber volume is on a 401 Nailhead?

Many thanks
Gus
 
Gus asked this same question on V8buick.com. There are too many unknowns to get anywhere close on the compression. The biggest unknown is what pistons are in a 50+ year old engine that he has not owned from new. Best guess is somewhere between 9 and 10:1.
 
NOT IF the engine rebuild contained off the shelf cast pistons & the Felpro gasket set.
In reality compression could be as high as 8.25-1 or as low as 7.8-1
AGAIN, too many unknowns to know exactly.
Just the addition of the Felpro gaskets on a 401 lowers the compression approx. .77-1 from the shim steel gaskets originally installed at the factory.
Real truth numbers the ratio from the factory is closer to 9.75-1 that's with a piston in the "Hole" at .040" which is kinda rare.
The majority are in the hole .055" which lowers it even more.

Tom T.
 
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