Heads are bad on my old 239. Block is good. I can rebuild the 239 heads; however, I have a set of 312 heads with matching 4bbl intake that will bolt on without the usual intake port matching problems. Question: will the 312 heads (identified by serial number) fit the 239ci engine? I acknowledge that the matchup w might be "putting lipstick on a pig"; however, I am in a time crunch and the question remains: Will the 312 heads work on the 239 ? Thanks! 

Some will and some won't there are 2 239 engines match up the head gasket that will let you know.

What version 239 do you have? ‘54 car or ‘55 truck. If you have an early 239 the water passages won’t line up. You need to drill a water passage in the block at #4 and#8 also weld the little triangles to support the new head gasket..

  Dennis in Lititz PA

Thanks for the reply!  A funny story on myself: Years ago, I stayed overnight at a motel in Letitz. When checking out in the morning, much to the amusement of the two female desk clerks, I asked where there was a good place to have breakfast in your town; however, I pronounced the name  as "le Tits". They giggled and tried several times, to my discomfiture, to teach me how to say it, without success. Finally they helped me out by making me repeat the word "lettuce". Then I knew how to handle the name while I was in town and not embarrass myself further. I guess that what happens to southern boys when they wander up north! 

Won't the intake valves crash into a standard bore 239?  Maybe the bores would have to be notched to clear the valves.  Dennis, I realize your bores are no longer standard, have you ever put G heads on a standard bore block?

John - "The Hoosier Hurricane"

John, I have G heads on my 239 since 2013. Standard bore 272 flat top pistons and a 312 crank.

  Dennis in Lititz PA

Who wouldn't want to stay in "Le Tits"?  I know I would. 

272 piston are.125 over 239.

Yup, I didn’t know anything about sonic testing when we did that.

  Dennis in Lititz PA

G headed valves will clear the 272 bore, Ford put G heads on 272s in '57.

John - "The Hoosier Hurricane"