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
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.
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 ]