You can see the numbers we are looking for here.
Get a mirror and look on the bottom of the exhaust side for a casting number.
C2242 or C6733 is the standard A head and is unpainted aluminum.
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C7707 is the C-type head and is generally painted red in the valley only.
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The C head has better porting and generally has a letter C in the valley.
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These are the general rules, but if you find a head that varies from these rules, we would love to hear about it.
Restorers have been known to paint a standard head red not know…
I, too, have a head without a serial number in front of the front spark plug, and I have always assumed it was a dealer ordered replacement from factory stock.
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