I always thought the numbers were fairly important as to a date, but seems I read somewhere on here a while back that they didn't really mean much? I have a head which has a 2 and under that is another 2 and then 15. I have no idea as to how "authentic" it is to the 15 touring it's on. A 16 motor I have seems to be complete and "authentic/original" and has the number, 12 and under that a 2 and then 15.
So my question is, what are those numbers????
I understand it is month and date the head was cast. It does NOT indicate year. It may be near the engine casting date, or not. Your opinion may vary.
On cylinder heads from 1910-1911 and early 1912, the numbers are just above the Ford Script.
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The single numbers (and letters) sometimes found at the very rear of the head are thought to be "mold numbers" to identify which mold a particular head came from so to be traceable in the event of a casting issue which might show up during machining...etc. There are no Month and Day dates at the very rear of the head that I have seen. When a head does have a casting date it is most often found straddling the center head bolt as shown in Keith's picture above. I have also never seen a head with a year number along with the Month and Day. The block has Month, Day, and Year typically at least through 1916 that I have personally witnessed and perhaps they ran later too. Those are typically found on the left side of the block and to the right of the water inlet.
I have heard the mold number theory, but I believe every mold number I have seen on heads has the first number between 1 and 12, and the second number between 1 and 31.
Let's get a list going of numbers in cylinder heads.
I have a 1913 type low head (with the square casting bosses) marked 7-24.
Agree with Keith - never seen a head that did not have a date on the rear. The mold identifier is on top of the water outlet at the front of the head, it is a letter.
I also have a head with the "circular date" design that was on the side of some engine blocks. The numbers are
Sorry, no pics
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Mine has what looks like 17-5 but the 5 or 17 is upside down. Or its 5-L1 but based on your comments, probably not.
The engine block is cast 82913 and serial C5383 FYI