| 35ford | -- 05-28-2012 @ 5:52 PM |
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What year are these heads correct for and are there any advantages to run them on a standard 24 stud engine?
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| kubes40 | -- 05-29-2012 @ 9:46 AM |
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"A" heads as you term them started in 1939 and ran through 1941. Most often the "A" was between the 2nd and 3rd cylinder. The earliest version of this head placed the "A" very near the front of the cylinder head. Contrary to a somewhat common belief, there is a definite right and left head. Advantages? Versus what?
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| supereal | -- 05-29-2012 @ 3:29 PM |
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As Mike points out, the left and right side heads are not always interchangable. Some were, such as the 99T set for 39-41, and the 59A, used from 45-48. There is a complete listing on page 229 of the green book. The letter A or B appears on all heads from 32 thru 48. The important number is the prefix, such as 81A, 81T, 99T, 29A, or the familiar 59A. There were design changes made for valve clearance between some years, requiring cutting the valve pocket for clearance. Also, the cooling passages and gasket design were modified, and piston design was changed from flat to domed. If anyone wants info on those, I'll post the page from the Ford repair manual # 3666-47G. These could conceivably provide some advantages, but the main difference, if any, would be in the compression ratio. In most cases, swapping wouldn't produce much effect in performance.
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| Stroker | -- 05-29-2012 @ 4:13 PM |
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The only thing I'd like to add is that some of the earlier 24 stud heads do not have adequate radial inlet valve clearance for later 24 stud blocks, so it is always a good idea to "clay" any head that is not going back on its' original block. I'm running early (38) heads on a 59A block, and I had to relieve the inlet valve area of the head about .030" for inlet valve clearance at the outside edge of the inlet valves. One question we often get is in regard to aftermarket cams. Many of these have more net lift, and thus require additional clearance above the valves. Many stock heads have been repeatedly re-surfaced over the course of their often interesting lives. When going to a high-lift cam, clearance checking with clay is mandatory, and often the only solution is to substitute aftermarket alloy heads when using aftermarket cams. It would help us a lot, if you would be a little more specific regarding your block, heads and application.
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