I’m currently replacing piston rings and can figure out the size of the bolts that connect the head to the base . Ive used a 1/2 on half of the left side head and the right side the 1/2 doesn’t fit on the longer bolt . Is it a special socket ?

 

Are you dealing with a stud, or a bolt? If its a bolt, a standard socket should work. If its a stud, try a deepwell socket.

 

Oddly, my Snap On 1/2" deepwell got hung up where the bore of the socket was too small to go onto the bolt too.
Normally the diameter of a bolt with a 1/2" nut is 5/16"

I bought a hardware store Chinese socket and that didn't fit either, but since I was only $5 into it, I bored it out on a lathe.

 

The studs should be a 1/2 inch 12pt.