What is the Engine in my M37??

[natendee]

I recently acquired a 1951 M37 and am trying to identify the engine that is in it. I'm new to this but my understanding is that if it were the original 230 the head would be 23" long. The head on my truck is 25" long. Based on what I've read this could be a couple of engines including the 251. Unfortunately I can make out no serial number where I would expect to see one on the front driver's side corner of the block. Also there are no data plates on the glove box. Markings on the engine include "J261" cast into the block and "M153 675164" cast into the head. Below are a series of pictures of the engine. Does anyone know what this is or where I may find more info on it?

 

[thmpr]

Without checking numbers, looks identicle to my Canadian 251.

 

[just me]

Look on the curbside for a serial number, also. Not just on the streetside front.

 

[rtk]

Looks like somebody in the past installed a 251 instead of the 230 . It's missing a lot of the military items you would expect to see . No big deal , just work with what you have . The radiator is moved forward on the 251 so there is room for the fan shroud . Is your MV converted to 12 volt ??? Looks like a fun project !!!

 

[natendee]

Yes it's been converted to 12V and it's a mess. Planning to convert it back to 24V. Is that the correct radiator on this one? I'm assuming it's in its original position which is why the shroud is not there.

 

[Black Ops]

It looks like a civilian engine. Usually there is a plug over the number six cylinder you can remove to measure the stroke which could help narrow down what it might be.

 

[zak]

This is a Canadian 251, compare yours. Look at the left front motor mount its moved forward for the 251

 

[natendee]

It looks like a civilian engine. Usually there is a plug over the number six cylinder you can remove to measure the stroke which could help narrow down what it might be.

Thanks for the suggestion!

 

[natendee]

This is a Canadian 251, compare yours. Look at the left front motor mount its moved forward for the 251

Thanks for the reference images. Looks similar though I'm not entirely sure what details to look for.

 

[rtk]

The radiator looks correct , once it's moved forward it should be ok . If memory serves me ??? I think there is a change in the hood length or sheet metal on CMP vehicles to accommodate the 251 engine ,not sure about that . just so you know 230 engines are pretty common still , so if you wanted to change it back you should have no problem .

 

[teletech]

I also remember the Canadian vehicles having a longer nose. FWIW, the 251 makes a lot more power and torque than the 230.
I remember mine liked 50MPH really well but wouldn't complain about 60 for short bursts.
I also think they crack exhaust manifolds less frequently?
Just something to consider before chucking it out.

 

[natendee]

Thanks for the input. At this point I'm planning to leave the 251 in it.

 

[Evil Dr. Porkchop]

Thanks for the input. At this point I'm planning to leave the 251 in it.

How do you know it's a 251?

 

[natendee]

That's assuming it is. Still need to measure the stroke.

 

[Evil Dr. Porkchop]

That's assuming it is. Still need to measure the stroke.

My guess is it'll be a 236... and that's just a guess.

 

[zak]

Biggest and easiest sign is to check the front motor mounts. If their forward of the stock ones you have the bigger block not necessarily the 251 thought. I certainly not an expert to tell you what different displacements this block came in.

 

[Storm 51]

It would probably help you a lot to talk to the guys from Canada. There is a guy on here who goes by RMS that lives near Vancouver, B.C. that has rebuilt and modified a lot of the 251 Canadian trucks.

You might try sending him a PM. I'm sure he could help you a lot in figuring out what you have.

Good Luck!

 

[KaiserM109]

This is a Canadian 251, compare yours. ...

Nice work, zak!! Nice tribute to an old work horse.

The M715 series by Kaiser was supposed to fill that niche during the Vietnam war, but they were garage queens. My old M37, a rebuilt 1950 model, got me home every time, even after being dunked in a canal once.

 

[natendee]

Measured the stroke and determined that it is a 237.