Hi all, I’m trying to find out if the 383 Engine in my 71 Cuda has the 9.5 or the 8.5 compression. The block casting is 2468130 dated 9-11-70 the heads are 2843906. Not a numbers matching car and couldn’t get much info from previous owners.

 

You would need to know what heads it has are they stock pistons has it been re bored What is the cranking compression reading. That a side for a 383 most likely a 9.5 to one

 

I would say 8.5.1 C.R.