Blocks 1949-1964 Functional Differences


Functional Differences

Parts might exchange from 1949-53 303, 1954-56 324, 1957-58 371 engines. 371 and 394 cranks might interchange (same stroke), as might 303 and 324 cranks (same stroke). Cams should be interchangeable. In general, the 324 and 371 can interchange a lot but not to the 394. Parts will not exchange with post-1964 engines (260, 307, 330, 350, 403, 400, 425 and 455). These 1949 to 1964 blocks are physically very different from the 1964 to 1990 blocks, at least in appearance.

303 and 324 use the same deck height. The 371 and 394 have a taller deck height than the 303 and 324 engines.

The 394 might have a weakness in the cylinder heads, and they have a tendency to crack.

You could call some for the cam grinders that were doing cams back in the 50's, like Isky and Crane (check Engle also), to see if they may still have some lying around. You'll probably need to have a stock cam reground. Cams for the 1964 to 1990 Olds blocks wont interchange with the 303, 324, 37 or 394.

There will be some trouble finding a few things, but generally, you can find any stock parts you need. Price is the problem. Parts for these beasts generally run more than the more common motors (like a $100 gasket set). Rod bearing and timing chains should be fairly easy to find locally for a good price. Kanter Products offers a complete line of parts to rebuild a stock 394.

Exhaust manifolds also differ greatly. For headers try a custom header shop.

The J-2 Tri-Power setup will NOT fit the 394. There were differences between the 371 and 394, I believe in the port sizes. The 394 intake passages are much larger. Also available is a dual-quad intake for a pair of 625 CFM Carters.

You can save the carbs and linkage. As far as performance intakes, Offy used to make intakes, like dual quads, 4 2bbls' and things like that. Offenhauser did make a nice 3x2 intake manifold. The problem now is finding one at a reasonable price, to make yours a rare Tri-Power Oldsmobile. Your best bet for high performance, is a stock 4GC intake with a 625 CFM Carter AFB. Besides, the Offy manifold is aluminum and looks better.

Hilborn had a fuel injection setup of these things, at least I think it was Hilborn. I remember seeing a trick dragster with a late 50's old, port fuel injection, and stock velocity stacks for each intake. There were blower intakes for these guys as well.

There is an old junkyard in NE Georgia that has about 5-10 1960 to 1964 394's, if you need spare parts/engines.

[ Thanks to Doug Ahern, Bob Handren, Isagil, Scott for this information ]