273 Commando Piston Dome Volume

krazykuda said
The Edelbrock LD4B is made for the 66 and later head bolt pattern.... The D4B is the one made for the early 64 & 65 heads with the unique 5/16" bolt pattern...

I would recommend using a set of 66 or 67 heads instead to be more compatible with the bolt pattern, or you could enlarge the intake bolt holes in the manifold so the bolts will go in properly... But if you want to keep the intake manifold virgin, then I would go with a set of 273/318 heads from 66 or later... 66 & 67 will have a little smaller combustion chambers to help keep the compression up.... THe edelbrock intakes are getting harder to find and it may be easier to find compatible heads for the LD4B or you will have to modify the intake bolt holes to use the LD4B on the early 65 heads...

I’ve had 8 heads crack tested (4 x closed chamber & 4 x open chamber) and they’ve all come back cracked, either through the combustion chamber or around the two end bolt holes closest to the exhaust manifolds. I’ve just payed for a NOS set of closed chamber heads, which is what I was wanting anyway to chase the CR of the Commando. I know I’m going to have to alter the bolt angles on my LD4B but I’m ok with that, as you said these Edelbrock manifolds are getting hard to come by and these cracked heads have put a real dint in my budget. I appreciate you taking the time to reply to me, it’s really appreciated mate.