Because of the difference in pin height the 256 piston sits up higher in the cylinder ending up at the same point as the other engines.

  Dennis in Lititz PA

Everything else equal, if only heads are swapped, then clearance will remain the same.


Lawrenceville, GA

Ok with the difference in the stroke, if someone were to just put 272 heads on a stock 256 2V it seams it wouldn’t be as efficient. There would be a .020 difference at TDC correct? Whatever the PO did it must have ran because there is plenty of grease and grime under valve covers and around head to indicate miles were put on engine in this configuration. I assume the head could have been shaved? I need to unstick engine any way. Marvel Mystery oil in cylinders let it soak a few days?

Your 256 is the same bore as a 272, it has a 3.10 stroke instead of a 3.30 stroke. To turn it into a 272 you would need a 272/292 crank and 272 pistons because the pin height is different on the 256 pistons.

  Dennis in Lititz PA

I’ll need to clean it up, check cylinder bore size and give it some thought. I’ve got plenty of metal work to do on the 56 F100 cab first.

someone might want it.you can make a 272 or 292 out of this block.

Ok since the engine isn’t rotating (yet) I pulled the bell housing, clutch and fly wheel. After all that looking at crank flange it appears to be a 256. Bummer. I also noticed the drivers side head has a different casting number. E1N or something like that. I will continue to look it over but not sure if I want to invest any money in this one. I have a 351, 460 and a Cadillac 429 as options as well.

they still used 256's in busses in 56!

 lincoln/merc. y-blocks &mel's                                                               bucyrus, ohio.

There were two 239's, one cast in DEARBORN (DIF) and the other in CLEVELAND (CF).

The DIF 239 was the oddball engine and saw assembly in the PASS CAR. The CF 239 was a different design, forerunner of the 272-292.and was used in LT. The 256 was used in PI, MERC (both 1954)  and LT and HT (1954-1955). The 272 was introduced in 1955 as a running change, although cataloging shows it as 1956.

There is where the confusion is.

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The trans had already been removed so if I understand you you I should be able to look thru the hole in the bell housing at the rear crank flange. I’m currently looking at some pictures online of crank flanges. Also from reading if someone did put 272 heads in 256 block sealing between intake and head would be critical. Looks like a 272 has .030 more stroke as well. I’m not even sure if this engine ran. Could have been someone swapped parts couldn’t get it to run and gave up? I got the frame and engine for free so nothing lost. Thanks for advice I’ll start digging more into it tomorrow.