• If you like antique engines, vintage tractors or old iron, please register and join us. When registering, please provide your CITY and STATE as your location!

Cummins Models H and NH Diesels - what were they used on?

Robt.

Subscriber
Last Subscription Date
07/10/2019
Picked up a "unit rebuilding" manual for these engines and was wondering what they were used on/in? Manual is called "Bulletin No. 6301-A" and dated december 1948. Nice quality paper and printing with lots of photos; too bad they're not all that good. It's in a Caterpillar Service Magazine cover which I assume is unrelated?

Thanks!
 

Rodrigue Caron

Registered
Last Subscription Date
02/25/2012
HI all,
Cummins engines were used about every were ,name it, trucks ,marine,generator,industriel of any kind.At theses times they were one off the biggest if not the biggest engines manufactureur of diesels engine in North America. HI Rodrigue.
 

ListerDiesel

In Memory Of
Age
73
Last Subscription Date
10/24/2016
14 litre straight-six diesel, used on a lot of UK independent trucks like ERF, Foden and others. Ford used the V6 and V8 Cummins in their larger D series trucks as well.

Got a book somewhere as well, we had a customer in the 1970's with a four wheeler truck and drawbar trailer that we used to look after.

Noisy as hell but very reliable, 180hp to 240hp, there was a turbo as well.

Peter
 

ronm

Subscriber
Last Subscription Date
07/10/2019
Essentially, they are still being used-the N14 engine is still running in thousands of trucks & tractors....over 450 HP, electronic controlled.
 

John Schwiebert

Registered
The model H engine was 4-7/8 by 6 same as a lot of old Macks 673 Cubic inch displacement. With the NH the bore was not large enough for the valves so the bore was increased to 5-1/8 inch 743 cubic inches if I remember correctly.
 

ronm

Subscriber
Last Subscription Date
07/10/2019
The "classic" NH engines are 855 cu. in., 14 Litres, like the NT280, NT335, & so on. Without going out to the shop & getting my old Motor's Manual, I don't recall what model went from 743 to 855, as I remember, there was a "280" & a "big bore 280"...the old Emeryville IH that we had at the JD store had a big bore NT280, but everybody said it ran like a 335....I think it had been tweaked....;)
 

John Schwiebert

Registered
The 855 engines have a 5-1/2 inch bore. They had a couple of older early engines called like the "Super 250" and I think there were a couple other sizes. They had a longer stroke. Without looking I think displacement was 927 cubic inches.
 

dieselfreakcjw

Registered
hello all! i just recently sold a supercharged NHRS cummins to a fellow in texas i found the engine at the scrap yard it used to be in an industrial application but this guy is restoring a truck to put it in this engine is i'm guessing pretty early in production as it still has the cummins double disc pump
 

ronm

Subscriber
Last Subscription Date
07/10/2019
My old diesel instructor called the double disc pumps " boat anchors"....& he was old enough to know...
 

rvannatta

Registered
The "classic" NH engines are 855 cu. in., 14 Litres, like the NT280, NT335, & so on. ....;)
Agreed we have a retired log skidder with an H-6 cummins
in it. 2 valves and 672 displacement or so. 160 hp at 1800. Later they offered an HR-6 for revised and
an HRF --- revised and fast which turned up 2100.

The NH-220 was the basis of the 4 valve serires which later
got turbos and the like.

Our H6 was of the mid 1950's vintage and did have a PT pump.

It was still later that the displacement increased to the more familar 855.
 

Sooty Jim

Registered
Working on a two-part history piece on the H for Diesel World, since that engine was the product that made the company. It first made smoke on November 19, 1931 and it's descendants are still in production around the world, the last one here being the N14 of 2002. That's a "wow" factoid if there ever was one.

I'm dealing with several of the Cummins historians on this and some interesting details that have come up include:

- "NH" is likely not for "New H". There was no official proclamation on what NH stood for when the engine debuted for 1945, but back a couple decades ago, one of their historians interviewed some the surviving engineering principals in that development who said NH was for "New Head." Along with the new head came an increase in bore size to 5.125 and that increased displacement from 672 (448 for the HB-400 4-cyl) on the HB-600, to 743 on the NH-600 (495 on the NH-400). The '49-73 HR was a two valve version.

- The "H" in the model designation likely stands for "Hans," as in Hans L. Knudsen, the Cummins engine designer that did a lot of the nuts and bolts engineering on it. When he came to work at Cummins a few years before, the first engine he did was the Model K... for "Knudsen."

- The HA (first edition of the H) had 3.25" main journal diameters to 1935, after which they increased to 4.5". The entire series maintain the same crankshaft dimensions to this day. Also, the H series had an unusual feature.. an accessory mounting that was cast integral with the block rather than made separately and bolted on. This was another feature it retained over the years and was the only (or one of the very few) Cummins engines that had it. Interestingly, as Clessie and Hans were designing the engine, Clessie wanted a separate housing and Hans an integral. Each had sound engineering arguments for their opinions. Clessie respected Knudsen greatly, gave in, and the engine had an integral accessory drive from that day on.

- The Model H was intended as an automotive diesel as much as anything. In 1932, Kenworth was Cummins' first customer for H engines into trucks and the list of trucks using them in the '30s was fairly long (though diesels were not all that popular in that era). Cummins was still struggling at that point, so they put H engines wherever they could... including into a 1941 tank, an experimental variant of the M-3 light series.
 
Last edited:

Oil Power

Registered
I have a friend trying to sort out an old Cummins H in a Fedrall tank transporter. The engine will run but not above idle speed. Having an unknown history one thing I suggested was to check the timing. It has the original single disc pump and our Cummins manuals state these pumps should be timed on VS position which is approximately 90 degrees ATDC. We have found instructions in both a War Department Maintenance Manual and a MoToR Truck Repair manual, both stating the pump should be timed to TDC. The engine is presently timed to TDC. Does anyone know what is going on here? You would not think the engine manufacturer's manual would be wrong. If not where does the TDC timing come from? I am not aware of a variation in models of these engines having different timing.
Hugh
 

Mikey4026

Subscriber
Last Subscription Date
07/10/2019
Cummins, some models are good, some not!
I never had any respect for the V300 or V or VT903's.
The M11 and ISM were good engines, if the oil and coolant did not run all over the ground, caused by poor machine work on every gasket surface and a poorly designed rockerbox . Everything looks like it was milled with a dull chainsaw.
The N14 is awesome, the K series was the same.
I had a QSB that went 80,000 hours in a yard tractor. Yes eighty thousand hours! It would probably gone 20,000 more if the air filter had not fallen off!
I am really sold on the QSB, ISB series, don't much care for the common rail fuel systems, Cummins or anyone else's! Too many problems with all manufacturers in our fleet.
My nickels worth, probably worth only 2 cents!
Coming up on 46 years in the diesel repair trade.
Mike
 

pegasuspinto

Registered
There is NO timing on the disc/twin disk/PT pumps. These pumps simply regulate pressure, the timing is controlled by injection lobes on the cam.
 

John Yardley

Registered
I have a friend trying to sort out an old Cummins H in a Fedrall tank transporter. The engine will run but not above idle speed. Having an unknown history one thing I suggested was to check the timing. It has the original single disc pump and our Cummins manuals state these pumps should be timed on VS position which is approximately 90 degrees ATDC. We have found instructions in both a War Department Maintenance Manual and a MoToR Truck Repair manual, both stating the pump should be timed to TDC. The engine is presently timed to TDC. Does anyone know what is going on here? You would not think the engine manufacturer's manual would be wrong. If not where does the TDC timing come from? I am not aware of a variation in models of these engines having different timing.
Hugh
Cummins single disc pumps most certainly need to be timed. Set engine with #1 cylinder on compression stroke and turn engine till you are at 1 & 6 VS on water pump drive pulley, or on older models, when 1 or 6 stamped in flywheel appears in inspection hole in the flywheel housing, you will see an index mark on the flywheel as well as the housing, bring them into alignment. Remove plug from side of distributor housing and you should see the distributor collar timing mark (a small notch) visible in the inspection hole, if not remove complete pump from engine and rotate the fuel pump shaft to bring the distributor timing mark into index and present pump tp to engine without rotating engine. Remember that the SD pump meters and distributes the fuel to the appropriate cylinder so must be timed to the engine, if not misery will plague your house.
 

John Yardley

Registered
Cummins single disc pumps most certainly need to be timed. Set engine with #1 cylinder on compression stroke and turn engine till you are at 1 & 6 VS on water pump drive pulley, or on older models, when 1 or 6 stamped in flywheel appears in inspection hole in the flywheel housing, you will see an index mark on the flywheel as well as the housing, bring them into alignment. Remove plug from side of distributor housing and you should see the distributor collar timing mark (a small notch) visible in the inspection hole, if not remove complete pump from engine and rotate the fuel pump shaft to bring the distributor timing mark into index and present pump tp to engine without rotating engine. Remember that the SD pump meters and distributes the fuel to the appropriate cylinder so must be timed to the engine, if not misery will plague your house.
Sorry gents, my typing was getting ahead of my brain, the timing marks you want are 1 & 6 TC not 1 & 6 VS (Setting injectors or Timing Disc pumps are done at different points):bonk:
 
Top