raycan2

How do I ccheck the compression on my 440 to where I would know if it's 10:1 or 10.5:1 or what have you? Is the only way to check it is when the engin is torn apart?

moe7404

to get the numbers you are talking about you need to take engine apart and test the parts sizes and chamber volume. and do the math. the older car magazines should have good how to. the pressure on a compression test can vary much with as little as a piston ring not sealing good. if you have stock parts the stated C.R. from the factory will be very close.

Coronet 500

Well you should know your bore and stroke, the head gasket thickness and hole size can be estimated or use a razor and cut it back at an edge where the head and block meet and check with a feeler gauge.

One of the most important will be deck height (amount piston is below the block deck) maybe a search with block casting number and year if it's virgin, a build sheet if it has been worked would be best.

The cylinder head combustion chamber can be estimated with a head casting number and a web search. Then find a compression calculator on the web and plug in your numbers.

The most accurate method would be to remove a cylinder head then deck height could be measured and head could be filled with liquid to get actual volume. Any piston dish or valve notch could be seen and estimated.