Real reason for the X on the X heads

My Dad worked at Chrysler, about 10 years ago a friend of his that was a VP at Chrysler retores cars and was looking at a Barracuda that the owner said had X heads. He got a kick out of it and reminded my dad why the X was on the heads. Dad could care less about cars but here is the story in his words why the X is on the head.

“The X on 340 CID Cylinder Heads”


The Chrysler Corporation 340 CID engine was an enhancement of its 318 CID engine that had been produced since 1955. Both the 318 and 340 CID engines were concurrently machined and assembled in the Mound Road Engine Plant in Detroit, Michigan. The cylinder head castings for both of these engines were produced by Chrysler’s Huber Avenue Foundry,also located in Detroit.


The 340 cylinder head casting closely resembledits 318 counterpart and was difficult to visually distinguish. The two heads had their specific part numbers cast with 1/4 inch numerals on the exposed surface of the casting, but this difference was not readily discernible. These heads were processed concurrently through the foundry and their similarity in appearance, resulted in the two being mixed when palletized for shipment to the Mound Road Engine Plant. This obviously created a problem.


At this time I was the Product Engineering Manager of the Huber Avenue Foundry. To assist in the separation of these castings, I issued an ‘Engineering Change Request’ that provided for the letter ‘X’ to be prominently cast on the surface of the 340 heads. This change accomplished what was intended. The problem was abated, though I’m sure a few of the 340’s still became mixed with the 318’s on the pallets shipped to Mound Road.


There may be some 340 CID heads out there that do not have the X, but these were produced prior to the change being implemented.


William Kamradt

Chrysler Corporation

1955-1989