Re: V-8 engine conversion for '53 M37


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Posted by Alan Bowes on October 03, 1997 at 13:12:35:

In Reply to: Re: V-8 engine conversion for '53 M37 posted by Grant R on September 29, 1997 at 09:17:50:

: I bet your trying to save the original bellhousing so as to retain the factory rear mounting system and clutch linkage? I don't see any way of retaining the bellhousing, it's totally different. I have heard of 420 transmissions behind some early V8's, but I'm sure the front is different (input shaft, maybe the bolt pattern), so it won't help much. If I was you and had to have a V8, I would probably run a chevy 305 with the old style bellhousing, it has "side mounts to support the rear of the motor", the transmission hangs out in space, just like the original setup, and you should be able to adapt it over to the original frame brackets. Behind this run a SM-420 (chevy 4 speed transmission used in trucks to 2 ton or so, up untill 1967) cheap and easy to find. Your smart to want a small CID engine, it will help prevent breakage (drivetrain) problems.

: Grant

In my responses to Jim's original post, perhaps I should have clarified that I was talking about using the 318's (or other V8's) bell housing, and how it would require either modifications or an adapter if he wanted to use the original transmission. You are right, of course, that the original 230 bell housing won't bolt up to a 318 block. And even if Jim could use the original bell housing, the rear mounts on the old bell housing probably wouldn't be compatible with the geometry of the placement and mounting of the V8 anyway, meaning that the rear mounts would probably have to be modified. I think your suggestion about the small-block Chev engine with the mounts on its bell housing is a good one. I've seen some big-block installations that fit under the hood, but took up so much volume that it made it very difficult to fabricate reliable linkages. Weight is another factor. It would be nice to use something equal to or lighter in weight than the original engine to avoid suspension modifications.

My personal preference, IF I wanted a bit more ooomph, would be to rework the original 230 to safely coax a bit more RPM out of it and widen the torque curve so that it extends into a slightly higher RPM range. One key to this would be a stronger connecting rod and piston combination, plus dynamic balancing and better oiling. Some valve, port, and cam work could also be done. It could not only put out a bit more, but it would last even longer than a stock engine. I've done precisely this kind of work on some early OHV Chevy sixes and Ford flathead V8s with gratifying results. Naturally, this all costs $$$, so it's only recommended if you enjoy the challenge of improving upon the existing engine without losing its stock appearance. If you had a big budget, you could even do exotic things like have a steel billet crank machined for the engine. Then you'd have a wider choice of available connecting rods. For a lower budget, cross-drilling oil passages, nitriding, forging/casting cleanup, bead blasting for stress relief, and balancing will add strength and reliability to the original crankshaft and connecting rods. Cams can be custom-ground for a reasonable fee. A three-angle valve job, some light port clean-up for flow matching, relieving the backs of the valves, etc. are very minor mods that can reduce pumping losses and add some spark to the engine's performance. Ignition work on this would be challenging if you wanted to retain a stock appearance, but there are probably a few possible tweaks. Synthetic oil will add a couple of horsepower while providing more protection. One might also consider some light head milling or different piston tops, etc., etc. I think it would be great fun to see what the old mill will do without breaking it.

Alan



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