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Possible explanation for difference

From: Hank Dozier
Remote Name:
Date: October 22, 2002


Bob...We have run into this before, and the answer as to why 3 versus two isn't all that clear on Canadian polys. Best guess is the following. Early 241 Hyfires (Plymouth poly versions of Dodge 241 block) had 3 retention bolt covers. A lot of these engines were used in Canadian cars and trucks (including some Fargos). When the Spitfire (Chrysler) poly came out, it also had three retention bolt covers. This engine was produced as a 301. The supposedly Canadian only engines off the wide Canadian designed poly were 303 and 313 displacements. The 277, 301 (actually 299.4 CID), 318 and 326 displacements saw US duty, and some of these were produced in the US, others in Canada. Now we know the 303 got pinched by the US Plymouth Division for the 1956 Fury. However, due to the close dispacement of these engines (301 Spitfire, 301 Wide Poly, and 303), I think the Canadians settled on 3 retention bolts per cover as a more robust solution (from experience with the 241 Hyfire), and heads/rocker shafts were produced accordingly. It doesn't take much to put that third stud in the center, and the valve cover tooling change would have been minimal. It also would have clearly marked a "Canadian" engine, as well. All this is conjecture from conversations, but if not true, its pausible. Anybody else have DEFINITIVE alternatives for the bolt hole count difference on Canadian versus US polys?


Last changed: July 19, 2018