360 in a ’40 Coupe

Tech Question


Lars Ivar Kvissel, Elverum, Norway, 1940 DeSoto Custom Coupe

Hi Rick! I have a 1940 DeSoto Coupe wich I have owned for 30yrs. Got it for free when I was 17! Now for my dilemma. I`m in a process ofrebuilding a 392 Hemi to put in it, but for this summer, due to budgetproblems, I have to use a 360 2 bbl I have had for years. Will any 904 transmatch the 360? I`ve been told it has to be a 904-998 or 999 if its going tobe OK. I have a rebuilt 904 from a 318 on hand, but been advised to turn itdown if it`s not from a 360. Others tell me otherwise!



First off, I will assume you mean a dead-stock A-904-A from a 318 car, notone that had been “built” (read: beefed or modified), since there isabsolutely no problem building a 904 to withstand anything short of anuclear holocaust, with enough money invested in “race” internals.

If it is dead stock, I think, if you just cranked up the line pressure 3 or4 turns, or, even better, invested a few bucks in a shift kit, it would livefor quite a long time. Of course, this guess assumes that the transmissionis in good health now!

Just remember to use the correct external-balance-360-weighted torqueconverter, or weld the weights on, or use a pre-balanced drive plate. Alsoremember that, for balance-specification reasons, there were two basicgenerations of 360s: 1971-1992, and 1993-up. If yours is an originalcarbureted engine, you can be sure it is the early variety.

Now, I know you didn’t ask this, but, overall, I am against the 392 swap.While the “eye candy” aspect is hard to argue with, you’ll just be adding SOmuch weight over the nose of the car, needlessly so. How about a “built” 360(425-450 HP is so easy), or even a big block? Gotta have a Hemi? OK,junkyard 5.7Ls are now plentiful — and cheap. You could even build that 904to live behind the 5.7L!


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