The Ford Barn - 39-42 heads

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- - 39-42 heads (https://www.fordbarn.com/forum/showthread.php?t=20954)

Do all those early 24 stud heads 39-42 have the same cc chambers? I know the A heads really pump up the compression on the 239 engine. I know you have to do a little cutting in the top of the valve pocket to use them on the 59 engine. I know the 40-41 heads have an A in the center, I don't think the 39 head do. Is that correct? Thanks Walt

I thiink that the dome is a different shape for the 3 1/16'' pistons, the center leaves a big gap on the top of the 3 5/16'' piston... I looked to use a set on an engine I am building now, did not like the taller dome... Karl

39 heads have the A.

There has been a chart posted over on the HAMB giving a lot of info about head chamber capacity. The short answer to your question is no. Chamber capacity varies quite a bit.

late 1938 - 1941 used the same heads: 81A-6049-A and 81A-6050-A with an "A" in the center of the head.

According to the Ford Service Bulletins there is very little difference between any of the 24 stud, iron heads with the exception of the "T" heads. The best of the Ford iron heads, older than 1948 are the 59A-"B" heads. The 81A heads are listed as 77-79cc. The 29A is listed as 78-80cc. The 59A-A head is 77-79cc and finally, the 59A-B head is 73.5-75.5cc.

The dome contour radius spec is the same in the "A" head as the 59A head. The differences are in the pistons. I have seen 4 different piston domes and would not be surprised if there are several more. None are a perfect match for the Ford design. Too, each aftermarket head manufacturer applies a different dome contour. About the only way to blueprint is to make a cutter which matches the chosen pistons and re-cut the heads. For performance and efficiency it is more important to have the piston to head clearance as tight as possible at the outside of each bank. For that reason I usually angle mill heads, ream the stud holes and reface the washer spotfaces on aftermarket heads.

Thanks guys for the info. Walt