Cummins NTC-350

That small spring and screw are for your idle. There are a number of big springs that have different lengths and different compression strengths, and it could be that yours has a spring that has a lower compression rate and that is what is allowing it to not build full pressure under power.

I would love to be able to give you a part number for a good spring, but they don't have numbers on them just colors, yet cummins still sells them by a part number, so maybe the shop you got the button from can help you out.
 
I'll have to call the shop that did my pump work and see what the deal is. I may pull the button that is on it now out and put the next one in line in it. I haven't lost any free play since adjusting the clutch two pulls ago.

As far as fuel supply could I rub an inline electric transfer pump between the tank and filter? Or is that pressure going to mess with the seals and such on the fuel pump?
 
It won't mess with anything, but with the PT fuel system the gear pump only pulls what it needs for the supply.
 
Right I understand that the PT pump is the transfer pump a d fuel pump all in one. My thought is that if I plumb an electric pump up to "push" fuel through the filter and have more supply there if I am starving the pump of fuel.
 
If you really are starving the pump which I doubt one thing you will have during hard acceleration on the road is that your pedal will go dead and not do anything. I doubt yours is doing that, and like I said a filter change will fix the issue.
 
Here are a few pictures of the fuel lines.

On the head that has the return you have to space the feed line elbow out to clear the return fitting. You will need a 1/8" NPT male to male coupler, a 1/8" NPT female to female coupler, and a 1/8" NPT male to -4 AN elbow. The feed line for te other head you can just use the elbow right out of the head.
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This is out of the solenoid, I have the tee plumbed in to be able to pull the pressure reading.
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Finally got a video, not the greatest but you get the idea of how this baby motor runs.

A068B306-CF2C-4D3B-9165-6CEA0C0BDEB4-754-0000009CE8CA931F_zps155fb6f4.mp4


I am down to a number 12 fuel button now. I did see 260 psi going down the road last night. I have one more button to go and I'll be at a number 7. Have 2 or 3 pulls left this summer so I think I'm going to drop to that button. I was overly happy with the way it ran yesterday. Right off the line I thought it was going to die and I thought about pushing the clutch in, but I got after it and it came to life and pulled good. At the end of the track it actually pulled. Previously it would get a load on it and die in a hurry. Yesterday that load came on and it kept pulling but did die out a little, but not as bad.
 
Mine actually spun out last night for a change, I switched to a pump a friend had that has a 1 1/4" gear drive on it and it really woke the injectors up. Now I think it needs more air, but I only have two more pulls so I may leave it alone.
 
What did the big 1-1/4" drive pumps come off of? Did they come on a big cam? How do you identify a big drive to a small drive?

I would love it of I could get my truck to spin out at the other end of the track. But I just don't have the rpm or power. Once mine starts to loose rpm it seems to almost die. But I guess that's just the nature of this engine. My dads Cat can drop 2-300 rpm and just keep pulling, but again just the design of the engine. I guess I just need more rpm! I am also only running 40 lbs of air in the tires. I probably should be running more but if I run any more it gets to hopping and then pulling is no fun.

A couple of older guys were pretty impressed with my truck yesterday. This old guy was asking me all about it, what I had done to the motor trans and rears. I simply told him, "Nothing, it's pretty much a stock 350 with a little fuel turned to it." Which is the truth. After the pull he sought me out and says, "That was a hell of a pull for just a stock 350!" I love that stuff!
 
None of the big cams ever came with a 1 1/4" gear pump, the largest I have seen is a 1" normals ones are 3/4". You would have to see the difference in the housing to be able to spot an 1 1/4" pump compared to the rest, the rear housing is longer to hold the longer gears as it is the length of the gear that they measure by.

Timing is everything, and one reason the small cams will not hold on to a pull, also the governor setup on a cat plays into that as well. My big cam lugs fairly well.
 
Seems to me like your truck pulls pretty damn good! Is that with the 1-1/4" gear drive? What did the pumps with a bigger gear drive come on? KTAs? What what is involved to put one on a smaller drive pump?

How about that Superliner? It looks pretty familiar. Do you know the guys name? Sounds like it has an inline six cylinder not a V8. We saw a guy at Antrim's Dyno Day very similar to that truck with an inline six that made 770 hp. Which I thinking pretty impressive for that little motor.
 
The big gear pumps came on the k38s and larger engines. The guy at diesel controls said that it wasn't really needed until the injectors get up into the 290cc range. It's not much to swap one; just have to have longer bolts and the pump. It's about $970 from cummins.

The black superliner belongs to a friend if mine and it is a E9.

My truck is running okay, but there is still more left in it that I am going to coax out over the winter, I am becoming a firm believer that whomever does the injector work should do the pump work to match what they built you for injectors. The 1 1/4" did really help, by if I wasn't running a big injector it would have been noticeable, my small pump was perfectly capable of keeping up with my old injectors.
 
When I had Antrim Diesel rebuild my pump this spring they sounded really excited to work on. I'd like to talk about injectors and the 1-1/4" fuel pump drive. That maybe a bit down the road though.

[ame]http://i1166.photobucket.com/albums/q619/RockinRam96/A068B306-CF2C-4D3B-9165-6CEA0C0BDEB4-754-0000009CE8CA931F_zps155fb6f4.mp4[/ame]
 
Boy, am I super happy with the way my truck pulled today. It did what I have always wanted it to do. It leaves there nice and spins out at the end of the track. Now granted, I was in last place again, it is what I think two nice pulls considering the trucks I am competing against, and my virtually stock 350.

I now have a number 7 button in the pump and boy has it made a difference. I would really like to know what a number 5 or 00 button will do. I don't have my pyro hooked up yet so I don't know what kind of exhaust temperature I have, but it isn't making much smoke, so I can't believe it is much over 800 degrees. But I know the truck is making about 20 psi of manifold pressure and about 300 psi of rail pressure.

Videos to come!
 
First pull it kinda fell on its face but picked right back up and pulled well. The second pull I left with a lot more RPMs, not sure how many because I still don't have my tach hooked up. But for your viewing pleasure....

1st pull:
[ame]http://i1166.photobucket.com/albums/q619/RockinRam96/1973%20Kenworth%20W923/IMG_2158_zps7f90f75c.mp4[/ame]

2nd pull:
[ame]http://i1166.photobucket.com/albums/q619/RockinRam96/1973%20Kenworth%20W923/IMG_0398_zpsc7ab0ac4.mp4[/ame]
 
Good deal, now it's time to get a modern turbo and maybe a little injector work and then you will be really surprised.

I'm working on trying to get some more air to mine before my hometown pulls this coming weekend.
 
Yeah that's what I was thinking. I am going to call the shop that did my pump work and see if I'd be better off with a big pump drive or injector work. I think I just want to step up to an HT60 at the biggest right now. Keep it fun to drive on the street.

But I my other thought is that I have a ton of money in it the way it is right now. The truck is doing what I want it to do. I have a long way to go to be competitive with the two 3406s, E9 and KTA that pull in our club. I have access to a HT3B, I may just slap that on there P&P the exhaust manifold and turbo, put a 00 button in it and have a goo time with it. I probably need tires now but I'd like to get next season out if them.

I don't know we'll see what the winter brings, I'd also like to do some cosmetic work over the winter so that may eat up some budget.
 
Injector work before pump work, they may not be able to get enough out of the small cam injectors that would warrant the larger gear pump.
 
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