question(s) for the Mechanics

Cummins had built the same basic engine from 1938 to 2000. The H model came out in 1938 it was 672 cid. (Intake and exhaust on right hand side 2 valves and external fuel lines. ) The NH 220 was 743 cid and came out around 1947. ( new 4 valve head intake left side exhaust right. External fuel lines and then the P-T pump came out around 1952) It was the standard throughout the ‘50’s. The NH 250 was the the first 855. It came out around 1957 and was the standard Cummins all throughout the 60’s into early ‘70’s. All other Horsepower was optional and each step up was extra.$$. The first big cam was the same as the small cam. Everything was the same except the 1/2 more diameter of the cam and larger followers.( smallcam was 2inch. Bigcam was 2 1/2) Most of the cpl’s still used the same grinds and cranks as the small cams. Block dimensions and bolt patterns and Stroke was same from ‘38-up to the last big cam. The cid was changed by larger bore liners.
Most of the early Komatsu’s were still using the 220 743 long before they went to the 855.
The Military was still using the NH 250 855 small cam mechanical up until 10 -15 years ago.
You can still buy new small cams made in china today for construction spec.

 

This is my NTC 350 855 SC in my ‘67. It is from one of my uncles old ‘74’s. FFC and suitcase waterpump. Looks like any other early big cam that came out later.
Engine should be painted white in a Pete since ‘65 but I like the cowpoop beige.

 

I can understand that and it makes sense.

Even if you do not work on it yourself, you should at least learn about the engine and about the truck so that when you take it someplace they're not going to BS you.

And it isn't only my point that a mechanical engine is better.

You could have an old truck that has a two-stroke Detroit in it. That's not going to have the power you want or give you the mileage you want or be modern enough. And if you value your hearing it's probably not a good choice.

You also could have a Caterpillar engine.

Caterpillar engines run nicely, but the problem is anything that you have to do to that engine you're going to have to dig very deep in your pockets. The name caterpillar equals big money in repairs.

I knew a guy that had the big Pete with the big cat. What a combination... When it came time to get close to rebuilding that big cat he practically broke down in tears in front of me over what it was going to cost him. Literally, he was fighting to hold back the tears. And that was a guy that can afford to buy anything on this Earth that he wanted.

So my point is that the big cam is an economical reliable easy to work on Modern engine.

You can get all of the power out of it that you want, you can get good mileage out of it.

It's not going to make you crazy with insane computer problems and you're not going to have to mortgage your house to work on it like you do with a caterpillar. And you're not going to spend $40,000 if you need another engine.

So yes the big cam is a special engine.

 

This is the NH 220 743 in my great grandfathers ‘51 Diamond T. It was originally a NH180 672 cid when he bought it new. Then in ‘58 it was overhauled and the larger bore NH220 liners were installed to make it a 743 cid. A very common thing to do back in those days. Also at that time the old disk pump was replaced with a PT pump. It has to be solidly mounted because it has to have the pulley on it to drive the air compressor belts the retrofit cast iron bracket that mounts it to the block weighs around 7 pounds. The generator on rh side is chain driven off of front gear train were they would have mounted the supercharger on the 2 and 6 bits 275hp or 300hp NHRS 743 cid’s. This is the only truck in our collection that has the fan low mounted and bolted directly to the end of the water pump shaft. Everything else we have they are high mounted on a hub above waterpump.
Put it next to a 855 bc and it is the same size block and heads externally. Looks shorter height wise because of no aftercooler, turbo, or Jakes. It’s a very tight fit in this truck and sits pretty low in the rails.
The “Old Gold” was the prettiest color Cummins used. IMO.

 

@small package

That's some very interesting information.

I did not realize the 250 was an 855. As I write this I think I remember reading that somewhere or seeing that, but I always associate the 855 with the 270 or 290 and up Cummins. Probably because I used to drive them. With the compression release and everything, lol.

And I did not realize the small cam uses the same aftercooler as the big cam. There is always more to learn..

You're right, that looks just like a big cam.

Can you post some pictures of that truck? Wow that engine is really stuffed in there! Is that a butterfly hood? That engine looks like new.

I bet that's a nice truck. Nothing like old iron.

 

You should link a page to the photos of your trucks or start a thread on them or something.

That's some really cool stuff.

 

I have thought about doing that if I can ever get going on my next project. But it looks like its gonna be a awhile yet. I’ve got a ‘73 352-110 Pacemaker coe Pete that had a 1693 325 hp. I believe It was the only Cat powered truck the family had. It was also one of the few that were bought used. They ran it till ‘90 and the engine was finally wore out. Pulled it and lost interest due to the cost being much higher than Cummins even back than. Put it all in a back corner of shop. Then sometime along the way someone “borrowed” the engine. So I’ve got that BC4 I need to overhaul and convert to early FFC and install in the Cats place. Got all the used parts from an Obama buy and destroy trade-in some old fool did. Nothing like having to put a hole in the side of a perfectly running block just because an ignorant person wanted to trade for a brand new emissions and plastic nightmare. Just need the $, time and Overhaul kit. Mounts are different in the rails etc.

 

@ small package,
When the stars align for you to get that 1973 Pete going - be sure to post the before, and after,
and in-process pictures. You guys have made me a fan of Cummins old iron. Beautiful pictures.
A 1951 engine in a newer truck, sounds crazy, but I'm all in! I hate complicating things with electronics.
I am also very impressed with everyone's detailed knowledge of the different series of these engines.

 

Now that takes me back.