360 vs 383

66fs said

No, the 383 had higher compression, 360's never had much since they came late to the game and began life, like the 318, as a low performance motor. It wasn't till they retired the 340 and gave the 360 the good stuff in 1974 that it went somewhere. Some of us noticed though, 360's used the same head castings as 340's and was a go to for good small block heads cheap.

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Not all 383's had high compression, the 383 2bbl had pretty much the same compression ratio as the 360. Agreed that the 383 had a high compression option that the 360 never did, but I would bet most 383's someone drags home to drop in their A-Body are going to be of the 2bbl persuasion.

And the 5.9 had a better ratio than the 383 2bbl, plus it is probably closer to the actual compression ratio while the 8.5-8.7 rated ratio on the 383 2bbl was probably more like 8.2:1.