Posted by Brian in Oregon on March 27, 2000 at 01:48:12:
In Reply to: Dodge 318 engine will it work in my M-37? posted by todd on March 26, 2000 at 23:55:12:
Yes, it will work. Check out Chris Davis' 318 conversion at his home page (auto link below):
http://www.webworldinc.com/johnson/m37web/
Gil Hugely also has a homepage with his 318 conversion. I lost my hard drive and his link. Perhaps Gil or someone else can post it.
Chris used a 318 mated to an automatic trans. Chris' 727 appears to have the long tailsahft. I've seen short tailshaft 727's made up that would allow (barely) two u-joints between the trans and transfer case instead of his one. I'm not sure what Gil used for a trans.
Ray Suit of Helitool http://www.uglytruckling.com is working a complete kit to allow a 318 and the original NP420 trans (which is the ticket for those with the original PTO winch). He is finalizing it and I hope it will be out shortly. His approach is to use a plate on the back of a bellhousing to adapt the NP420 to a particular later bellhousing that has ears, for which adaptor brackets can be made to fit the original frame points. I'm eagerly awaiting word of this conversion.
Monkeyman in The Land Down Under is taking a different approach. He is making an adaptor plate to go between the original bellhousing and the NP420. On the surface this would seem to be a "cleaner" install than Ray's. However, there are a few problems mating the 318 flywheel to the clutch all the way through to the NP420. On the plus side, he feels he can move the starter to the passenger side for more clearance for the PTO driveshaft. (The engine is off center in the M37 in case you did not know.)
I've heard from several folks about their experiences with V-8 cooling with the original radiator. It would appear with a nice, freshly rebuilt radiator, it will easily handle the 318. Even a 360. But if you try to run a plugged up radiator which may be OK for the 230, it will overheat with the 318.
HP and torque. You will about double the HP with the 318, and the torque will be doubled or perhaps almost tripled. Definitely with a 360. This presents no problem at highway speed. But in 1st gear (6.68:1), in low range (1.94:1) and with 5.83:1 axles you will have a HUGE torque increase on the axle shafts. If you are multiplying the math out to figure the increase, don't forget to divide by two since you'll have the front axle engaged. Regardless, you CAN break axle shafts and other parts if you are not careful. These are excellent off road vehicles, but they are 50 year old designs. In short, be aware of the limitations and don't be tempted to hot rod it. A performance engine is certainly not needed.
With the extra power from the 318, you can change the gears to 4.87's for better mileage. You will sacrifice a bit of rock climbing ability, but probably not much off road ability. I'm keeping the 5.83's in mine, though larger tires are a temptation.
BTW, Ray Suiter says the cleanest way to go with a V-8 install is to go with a 318 and a 727 or 4-speed auto trans with a married transfer case and sliminate the existing transfer case. He says there is less road noise. You will have to put an axle with a centered pumpkin in the rear. I've seen such a setup, with more modern axles front and rear. It was a nice clean job, but not my cup of tea.
Also on Chris' site is his friend Mikes 350 Chev conversion. Take a hard look at the differences in the motor mounts between his and Chris' 318. I'm not a Chevy fan, and I like to keep it in the family engine with (Dodge in a Dodge, Ford in a Ford, etc) but his 350 swap is THE cleanest install I've ever seen in an M37. Also look at Mikes power steering and hydraulic clutch setup.
Bottom line - The 318/727 (short tailshaft) is the easiest conversion (well, I have a sneaky feeling the 350 is probably easier - Chevies always are for some reason, but I like a challenge.) If you have a PTO winch model you can go to an electric winch or you can wait and watch for updates from Ray and Monkeyman.