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392 heads on a low deck (331/354) engine

From: Hank Dozier
Remote Name:
Date: December 09, 2002
Time: 08:34:42


The 392 is a unique head in that Chrysler made the ports longer in this head than in the 331/354. Because of this, the head is physically WIDER. This was done to allow the 331/and 354 manifolds to fit the raised-deck 392 engine. SO, the manifolds interchange between the two deck height motors, which is unusual, as both the Dodge and DeSoto used unique manifolds and kept the same physical dimensions for their heads. No one seems to know why Chrysler deviated from the philosophy of the other divisions, but it could be that since the 392 was the LAST hemi to be released, and since Chrysler was already suffering from the costs of these engines, maybe the heads were an easier (and therefore cheaper) alternative to making new manifold transfer tooling, especially since the heads were bought from New Haven Foundry (that NH on the head castings). In any event, since the 392 heads are wider, when you put them on a low deck 331/392, you end up with a VERY narrow space for an intake manifold, so this is why it is uncommon to swap "down" a 392 head onto a 354! I think you have room for a Hillborn manifold set (you have to shorten the crosslink), and possibly a DragStar manifold, although the carbs are going to be right up against each other. I would stick with 392 heads on 392s, and 331/354 on all the blocks (with spacer plates for standard manifolds, including blower bases - not needed for Hillborn or DragStars unless you want to use all the stock linkage, if you have it).


Last changed: July 19, 2018