Cummins NTC-350

RockinRam96

RockinRam96

Active member
Gentlemen,

This past weekend I picked up a 1973 Kenworth W923 with a Cummins NTC-350 855. This is my first class 8 truck, I bought it for a little restoration, puller, Sunday driver project. For the little knowledge that I have about big cube diesels, it's all Cat. My father has owned 4, 3406s and thats about all I know. So the common rail 855 is completely alien to me.

The gentlemen I purchased the truck knew a little history about the motor but wasn't 100% certain. I will be the 4th owner of the truck, the guy I bought the truck from personally knows the previous two owners. The 2nd owner of the truck bought the truck with a bad injection pump gear drive and had it replaced. The motor and transmission supposedly only have 50,000 miles on them. It starts right up just fine, the day I looked at the truck it was probably 25*F out, I turned the key, hit the button and it didnt roll over once and fired up. The only problem is that it smokes real bad, the owner said even after it warms up and even it the summer it doesn't clear up completely. Which most likely points to leaky injectors. But being Cat guys, my dad and I were thinking maybe timing is off?

Engine Identification is as follows:
Engine Number: 10334016
Family: 093
CPL: 0021
So. No.: 12873
Date of manufacture: 3/73

I have a ton of questions about this motor! First, what is is currently capable of, power wise? What turbo is currently on the truck? Injector part numbers? How to advance the timing? How to make pump adjustments for more fuel and RPMs? Turbo upgrades?

Thanks for any input and help guys. I know my best bet is to call a shop and discuss current issures and performance modifications but just thought I'd throw this out there for now.

Zach
 
Got any pictures of the truck?
I'd be happy to help with any questions you have on the engine. I can tell you now it's a Small cam. The new design Big Cam did not show up until 1978. Parts are still available in the aftermarket for you, and not too bad price wise. Through Cummins, old stuff like that costs tons if available.
There are all kinds of free and easy tricks to wake it up, so that's not an issue for you. Have you driven trucks of this vintage before? I ask, because this isn't one of the new cushy rides that anyone can just jump in and figure out.

I want to see pictures.
 
It's kinda rough right now. It hasn't come home yet, hopefully it can make the trip in a couple weeks. The paint should come back pretty well on it. Other than that the truck doesn't need much, just some cosmetic attention. The only thing you could say is messed up is the drivers seat is pretty much destroyed and at one time some on hit something with the drivers side front fender and tried to fiberglass it. But other that that the truck is 100% complete and everything works and functions as it should. For what I paid for it I couldn't pass it up. I am not looking for a big rig puller here just a little pump tuning and such will be just fine for now, maybe an upgraded turbo and injectors (if the budget allows).

As far as driving one of these old trucks, I haven't drove one this old. My father has an 88 KW W900B, 9 speed that has a Hendrix suspension under it, as well. Surely don't want to go on a long trip on a rough road with it!

For your viewing....

Image hosting, free photo sharing video sharing at Photobucket
 
Nice find. I've been entertaining the thought of an old school Pete or KW project.

I'll stick in here for motivation.
 
Timing has to be changed on the cam followers or by pulling the cam so you can press the gear off and change the cam key.

Not sure how much you want to get out of it, but a decent bit can be had just by modifying the pump. There is a thread in this section about tweaking the pump.

It's hard to tell what turbo is on it, a picture would help that out.
 
Like I said before not looking to get to extravigant at the moment with the motor. I'd just like to wake it up more. There are 5 or 6 guys that pull them around here regullary one Mack V8, a couple 3406s, and a couple 60 Series Detroits. I know I will take a bit of work to match those trucks.

As far as adjusting the timing can you go into a little more detail? Like I said, I am big cube Cummins dumb. And by changing the cam key, are we talking one cam shaft that controls the valves and injectors? Or are there two sepeate cams, one for the valves and one for the injectors?
 
One cam. If you look on the drivers side of the block, behind the fuel pump, you'll see three cam followers. They each have a particular thickness gasket/shim that dictates the position of the follower/tappets on the cam. We move them in or away to retard cam timing, and or, advance. Retarding cam timing makes more power.
I wouldn't mess with that right away :)
 
Not a bad looking truck, whats in it for a motor? 359 or 379?

I can never tell with these Peterbilts, my dad had two of them, one 359 and one 379. The only way I know how to tell the difference is the headlights. But I also know you can get 359 headlights for a 379, so that theory is thrown out the window.

Don't get me wrong I like Peterbilts but it seems like everyone wants one or has one that is tricked out. I'll stay with the KWs for now. But to each his own.
 
Is it getting right up to operating temp? Those old 855's just liked to white smoke off start until they were warmed up. If the thermostat wouldn't let it get to ~190 the white would never end. Actually if you walked by with an ice cream cone they would start to white smoke....LOL
 
RockinRam96 said:
Not a bad looking truck, whats in it for a motor? 359 or 379?

I can never tell with these Peterbilts, my dad had two of them, one 359 and one 379. The only way I know how to tell the difference is the headlights. But I also know you can get 359 headlights for a 379, so that theory is thrown out the window.

Don't get me wrong I like Peterbilts but it seems like everyone wants one or has one that is tricked out. I'll stay with the KWs for now. But to each his own.
Click to expand...

87 and older would be a 359. I'm with you, I would rather have a KW.
 
The day we look at the truck it didnt reach operating temperature. The owner said that even in the summer the truck wouldn't completely clear up. When I get it home, I'll let it get to operating temperature and maybe change the thermostat.
 
I'd prefer KW myself. The Pete is interesting because it's cheap.
Like real cheap, and local. I plan to look at it this weekend just for chits.

JSP has a good point on the engine temp.
 
SmokinCAT said:
Could be the injectors are worn, they will slobber if they have enough miles on them.
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They will slobber if they run cold even with good injectors. It would not be unusual to see dirty fuel dripping out the turbo outlet clamp, and exhaust manifold.
Run it up to 180-190 and see how it looks, and sounds.
 
Snedge said:
They will slobber if they run cold even with good injectors. It would not be unusual to see dirty fuel dripping out the turbo outlet clamp, and exhaust manifold.
Run it up to 180-190 and see how it looks, and sounds.
Click to expand...

Oh I know, one of mine is like that and even hazes a little when at temp, the other doesn't smoke unless its 30 degrees out.
 
Do the injector rocker arms need to have any gap set between the plunger and the rocker arm? Maybe the lash is set too tight and needs to be adjusted?
 
Got the truck home this weekend. Have only done a little tinkering and cleaning up. A bunch more to be done.

The engine idled real low so we got that picked up and idling a little bit better. The tach doesn't work so not sure what kind of rpms it is really idling at, but it sounds a bunch better. The other idle problem we haven't figured out is how I returns. It returns real slowly. I've been told this is a typical cummins characteristic. Any truth to that?

Smoke problems are still persistent. We got it home changed the fuel filter, ran some straight power service through it, which cleaned up the smoke a bit. It had about 45 gallons of old red fuel in it, which we drained and put new fuel in it with another can of power service. Smoke cleaned up a little bit but not gone. Have not had the truck to operating temperature, only about 120 degrees. Hoping to get it out today and get it to operating temperature and run more fuel and power service through it.

We are thinking the smoke is a fuel delivery problem. Either a problem with injectors or the pump. The pump has been changed recently, just before the previous owner bought it which was 7 years ago. The previous owner said the truck smoked the hole time he had owned it. Maybe the I correct pump was put on the truck?

Well here are some pictures to go along. It's definitely a work in progress. ImageUploadedByTapatalk1364734479.180254.jpgImageUploadedByTapatalk1364734507.649253.jpgImageUploadedByTapatalk1364734525.296107.jpgImageUploadedByTapatalk1364734557.480989.jpg
 
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