273 Commando Piston Dome Volume

Alpine White said

My mechanic as pretty switched on so can work it out. RC said they made them from factory 273 Commando pistons so was curious as to what the factory specs were. I did read on a thread somewhere that a guy did cc the pistons I have and they came in at 11.5.

Yep, closed chamber heads. It’s a 1965 Australian built AP6 4PV factory V8 car. We missed out on the 4bbl Commando version here in Australia so am building it to as close a spec as I can. I have an Edelbrock LD4B, Edelbrock 500cfm 4bbl Thunder Series carby, and have had my cam reground to a similar grind, bit more duration. Components are going away to be balanced this week then a dummy assembly to chase around 10.2-1. I’ll attach a photo of the car and a photo of the cam specs.

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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 intake 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...