engine

[squeeky0_50]

what motor is recommended other than the old flat head for the M37. I had 292 chevy with sm420 trans with 2,3, and 4th synchro, but i now have the original flathead and dodge transmission which I do not like. anybody have any ideas? would like to go back to chevy, not sure about another 292 or a V8. I would appreciate any ideas, thanks.

[RMS]

i like the flathead its a bit finicky but I think that's what I like about it. also I can change a hg on the side of the road in half an hour.

I could list off a bunch of motors guys have installed but I must ask what your intention is for the truck and what fuel do you like

if its something that sits for 6 months at a time I would go propane or diesel and steer clear of anything with electronic fuel injection

if your building a rock crawler I would look for something without a carb.

if your thinking of getting someone to do the work I would stick with the flatty and look for a better head/mill job to bump up the compression, chuck the carter then bolt on a weber and eliminate the points.
but if you want to toss the flatty and have someone to do the job right. I would see charls about a 4bt conversion

[Master Yota]

RMS brings up excellent points.

Anything that will rev higher than 3200rpm will improve the driving aspect with the stock gearing. GM V8s fit well and are a relatively easy swap with a 2wd transmission. The 230 is a relatively small (dimension wise) inline 6, so fitting a bigger 292 might create issues. But anything can be done with a little ingenuity.

[JimC]

I put a big block Chevy and an SM465 transmission in mine back about 1970, retaining the stock 5.83 gearing, with KS-22 No-Spin differential. I like that combination. Adequate power and speed.

I think Ray is running a 428 Ford in his.

[Master Yota]

I put a big block Chevy and an SM465 transmission in mine back about 1970, retaining the stock 5.83 gearing, with KS-22 No-Spin differential. I like that combination. Adequate power and speed.

I think Ray is running a 428 Ford in his.

I am running a 428cj in mine. I look at it this way; I don't see an M37 as a Chrysler product, I see it as an "M" series truck. All the big three auto manufacturers have built an "M" series truck at some point in their history, so swapping any engine from any of those manufacturers isn't a crime in my eyes.

My preference would be a rev happy small block if you're planning to keep the factory gearing. Another thing to consider, the smaller cubic inch engines are easier to keep cool, so the factory rad can often be re-used if its in good condition.

[JimC]

I live in the deep south and never had trouble with my stock radiator cooling. Top speed is a little over 111 mph (fast enough for me, particularly in an M37). Loud though. Course, the deep south is a far cry from Death Valley or the Salton Sea.

[ZGjethro]

Top speed is a little over 111 mph (fast enough for me, particularly in an M37). Loud though. .

That's just wrong! I can barely keep mine on the road at highway speeds (45mph tops) if there are cracks in the blacktop. Stopping is even worse!

[JimC]

That's why I only did it once. Scarier than the squirrelly steering was the worry that the flat windshield might blow back in on me. From memory (45 years ago), engine rpm was about 6500. I was running directional 9.00x16 Firestone Super All-Tractions, so it was quite a noisy ride.

I slightly disagree with Ray about the small block. I first put a 318 in mine and switched to the big block because the 318 was too anemic. Plenty of rpm but not enough torque. I strongly approve of his 428 cj though. That's a great engine choice.

[Master Yota]

The only reason I suggest a small block of any flavor, is that its cheap and easy to do. I had a fresh 305 (gasp!) in mine and with the stock gearing and tires made an enormous improvement on how it drove over having the flat head under the hood. I could hills on the hwy in 4th gear, at the speed limit, or burn the NDTs off without much hesitation, yet the torque curve was gentle enough that I didn't worry about twisting the axle shafts out of it if I got a little randy with the clutch and throttle...

Anemia can be fixed with a cam swap or simple upgrades. Of course the experience will vary within the chosen parameters...

[JimC]

I agree, with the exception that the big block is just as easy to do. It took me 3 days to pull the 230 and install the 318, and it took me 3 days to pull the 318 and install the big block Chevy. Neither were difficult. Primary installation control points were keeping the winch jackshaft in the stock location and keeping the oil pan clear of the front pumpkin. Biggest difficulty was sourcing a pair of GMC exhaust manifolds that would clear the frame without requiring whittling on the engine bay panels. Like Ray, I did have to use some common sense when applying the throttle or popping the clutch, and I became leary of loaning the truck out to folks who were ham fisted with it.