Small Block Heads

[QUOTE="Locomotion, post: 1972198460
I may have read somewhere why some heads are J, O, U, etc. But I don't recall what the theory was.[/QUOTE]
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The story I was told was. The letter on the heads was so the casting at the foundry could be sorted easier. I don't believe any 273 or 318 heads were ever lettered only the larger port 340 & 360.