RLJ (3/4/2017)
I thought if I needed a crank I'd step up to the 3.300" stroke of the 272/292 and make it a 272. More ci but keeping originality to the car.
So my question is the rod length is the same for 239/256 as the 272/292 from what I'm reading, so is there a difference in the pin height of the piston between the 256 and the 272? In order to make it work I would have to look for 272 pistons?
Dick
Dick. Going back to your question... Per JM's chart, the compression height of the '54 FoMoCo 239 and 256 pistons is different from the compression height of the 272 pistons. IF you are going to replace the crank in the 256 with one from a 272 / 292 engine, you'll need the later 272 pistons to go with the crank.
JM's chart shows the connecting rods for the 239, 256, 272, and 292 engines (except the HD truck 292 from '61-'64 AND the rods from the '62-'64 292) to be the same in center-to-center length and weight. The forging ID mark on the pre-62 rods is EBU. The later '62-'64 292 rods are C2AE. The '62-'64 C2AE rods are physically shaped differently from the earlier EBU rods AND weigh more. -Best not to mix EBU rods with C2AE connecting rods because of the weight difference.
In changing the crank and the pistons in your 256 engine, consider having the entire rotating assembly balanced.
NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York