Join Date: May 2013
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1973 Kenworth W923
About a month ago now I bought a 1973 Kenworth W923 with a Cummins NTC-350 small cam 855. I wasn't really looking for a truck but my father and I went to just look at it and I had to have it. The truck is 100% complete and as should be from 1973. There was also original paint on the frame from 1973. The paint on the hood and can is also in very good shape, a few chips here and there but I am pretty impressed being 40 years old. The interior is all complete, not missing any gauges or switches. It does need se attention but it isn't terrible.
Now for the motor. Neither my dad nor I have had experience with big Cummins motors. My dad has been a CAT guy forever and this is the first time we have been into a big Cummins.
When I brought the truck home it smoke really bad, white smoke. So we assumed it was the injectors. We tore the whole overhead apart, sent the injectors and fuel pump out to be tested and rebuilt. The injectors tested out fine and got cleaned up. The fuel pump needed to be rebuilt, so that was rebuilt. Put it all back together after searching and talking to a lot of people about the correct way to set the over head. There was no change in the amount of white smoke, so we ran the overhead a 2nd way. Still no change.
The first two times we set the over head we followed the firing order and the timing marks on the accessory drive, and setting each injector/ valve combo by the firing order. We had talked to a couple shops and old timers and was told the cam may be worn causing the bad white smoke. The 3rd time we set the overhead, we used a dial indicator to find where the cam follower was resting on the cam and tracked it all the way to the top of the lobe on the cam. Then we set the injector at the top of lobe to 70 in-lb. this seemed to be the best method yet. We have one more idea of a method to set the injectors we are going to try today.
This truck is pretty much a dream truck for my dad and me. My dad has wanted an A model Kenworth and since my dad bought his first truck I have wanted a big truck. It is going to be a continuing project with hopefully a show truck/ pulling truck. Right now it is going to be a puller, when I had the fuel pump rebuilt, the rebuilder increased the rail pressure to 200 psi from 160 psi.
I am really looking for help and info on this old Cummins. I am really hoping the cam isn't bad but all signs are pointing that way. Any help will be greatly appreciated.
Thanks guys and enjoy!