What is the combustion chamber size of Chevy cylinder heads from a 1969 307 truck engine?

There isn't a single definitive answer for the combustion chamber size of a 1969 Chevy 307 truck engine cylinder head. The combustion chamber volume varied depending on the specific casting number of the cylinder head. Different casting numbers resulted in different chamber volumes to achieve desired compression ratios.

To find the combustion chamber size, you would need to:

1. Identify the casting number: This number is usually stamped on the end of the cylinder head.

2. Consult a Chevrolet parts catalog or a resource like a Chevrolet engine rebuilding manual: These resources will list the combustion chamber volume (usually expressed in cubic centimeters) for each casting number. Online forums dedicated to classic Chevy vehicles might also be helpful.

Without the casting number, it's impossible to give you a precise answer. Expect the combustion chamber volume to be somewhere in the range of 64cc to 76cc, but this is just a broad estimate.