When I sent my engine to be rebuilt in about 2000, I just assumed you could turn a 239 into a 256. So it was bored +.125. It wasn’t sonic checked and it’s been running fine since 2003. Is there more meat in a 239 or did I just get ignorantly lucky? In 2013 I added G heads and a crank from a 312.

  Dennis in Lititz PA

Dennis.  That’s a good question but one I do not have the answer to.  Up till now, I have never had the need to sonic test the 239 cylinder walls for thickness.  Maybe someone out there has done that?

There are a multitude of 272 ECG blocks out there that have been bored 0.125” over to match the standard 292 bore.  I do come across those with some regularity and sonic testing identifies those 272 blocks that have been bored to become 292’s although the factory casting numbers may not be there.  Fred Jones engine rebuilding in Oklahoma did a large number of those and they would grind the ‘ECG’ from the blocks.  While those have been suitable for a run of the mill driver, the cylinder walls in those are on the thin side for any kind of performance application.  I have also seen 312 engines that were bored 0.125” over.  Some survived, many did not.

I do have a 1954 239 here that will be torn down in the near future for a rebuild and I will perform a sonic test on that engine.  As a FYI, that particular engine will be getting a set of custom cam bearings so that a later model Y camshaft can be used.  The distributor and oil pump will also be upgraded to the ’57 and newer pieces also.  It’s still being debated whether to upgrade the ’54 water pump, fuel pump, and timing cover to the ’55 and newer pieces.

Lorena, Texas (South of Waco)

Concerning the smaller water pump, I’ve never had an overheating problem, even when towing the camper over 7 mountains on US 322. However, it’s a one year only water pump, hard to get one. I carry a spare.

  Dennis in Lititz PA