Old School Engine Discussion - Small Cam Cummins Driveability

Not a toy, hauling 80K grain on 90 mile one way runs and backhaul occasionally back.

John

 

Been working the truck for the first part of the month. Went to a FF105 fuel filter and is seems to run a small bit better, but still sluggish on the hills. After a wet kit install and a new (used) pinned 5th wheel we have been able to run with an aluminum end dump instead of the steel hopper bottom.

Got a fuel gauge showing up today so we can do a snap test to see what the max pressure is.

We found the tag on the pump and after cleaning off multiple layers of paint found a pump code of 2433 which agrees with what is on quickserve. Does this imply a CPL of 233? I think so.

What should our fuel pressure be at that cpl build level? I am guessing 150psi?

If we are a bit low, should I be contemplating a button change? Or should I have them test the pump when I take it in for the overhead. I am definitely going to have the rack run. Probably has not been done since the rebuild.

New pyro installed shows 750-800 pulling on a hill.

Lots of info on the net about guys gaming the engine for pulls and hot-rodding. Not so much on how to tune for a daily runner.

What is it about old trucks and wiring problems? It's like playing whack-a-mole

John

 

I will put in my .02, back in the day, when you took the pump to the shop, you would tell them you wanted a little more fuel, 20% increase was about average and it wouldn't hurt anything. The shop would calibrate the pump for that. Yes, they will change the button and spring, and adjust other things so it would all work together properly. To be honest, this is your best bet. Now, if you really into horsepower, it's a little different ball game. It's doable but with a cost. Goodluck

 

Turn it up and drive easy. Best fuel economy that way.

 

Anybody familiar with Scheid Diesel in Effingham, Ill. They estimated $250 to run the rack and do a snap test on the pump. Sounds pretty inexpensive.

 

I've got a 1977 White road boss with a power tourqe 270 Cummins 13 speed with 3.58 rears and I put a #10 button and 400 torque spring in the pump. I haul logs with it and usually grossing around 88,000 to 100,000 and it will drag it 80 to 85 mph and it takes a hot b model cat to pass it!

 

I would find someone who really knows what they are doing and have them set it up properly.

I had the pump done on my NTC-350 a couple times back in 1977.
First time was done by "some mechanic" and it ran better than a stock NTC-350, had a .22 button, made black smoke and everything until the pump took a slug of water that scored the throttle shaft and other things.

Second time I take the pump to "The Man" who works at a truck dealership doing nothing but tune ups, setting up pumps and rebuilding injectors all day long and has his own after hours gig doing work for O/O's with their own shops.

I take the truck to him, he replaces the injectors with rebuilds from his own stock, ($25 per, exchange), puts the pump on the bench, goes through the entire pump, sets the rail pressure, makes changes to the throttle shaft, puts in a .32 button and does the top end set up.
Didn't smoke nearly as much, but man did it pull, picked up half a MPG, engine was a lot snappier.

After-cooler started leaking one day, took it to Cummins in Calgary and while I was there I had them dyno the truck.
It was making 350 HP at the rear wheels, in stock form they made around 290 HP if I remember correctly.

 

Back then that 238 was a 238 at the CRANK the 237 was at the wheels....grapes to watermelons comparison