Big Cam Cummins has low power

as found in another thread on here
http://www.dieselinjection.net/frames.html

by looking at what makes them go better, should give you an idea of what might make them go worse..

good luck!!

 

2k isn't bad.. you can take that motor to 2300 but I wouldn't go over that. they like to cruise about 1700.. much higher then new motors because they have so much less torque. the big cam is a 1350 pounts of torque if I remember right compared to the 1800 to 2000+ pound that 600 cat has.
the NTC300 means it's a 300 horse MTC(big cam) take a picture of both side of it and post it. If it is a big cam the three covers on the drivers side of the block arelike 6" tall and I think say big cam. But like I said mine is a bigcam II if yours is original it's a BC I or small cam. if it's replaced it could be anything. get the ESN number off that engine tag and I'll run it for ya.
check out this site http://www.freewebs.com/nevrenufhp/index.htm

 

by the way. my motor was also originally a 300. its been rebuilt to 400hp specs. MANY of the parts are all the same but the 300 has higher compression pistons then the 400 so it's not as easy as swaping the pump turbo and injectors.
oh by the way. best thing about the big cam is a new pump is only a few hundred bucks

 

My bet is still on the diaphragm. I have seen it too many times.

Another thing, unless you have what Cummins used to call the Formula engine, then the rpm range is between 1700-2100, meaning don't go under 1700 when pulling hard. Most people shimmed the pump to 2200-2300 for power and speed.

If someone has been messing with the pump, and you do have a big cam as opposed to a small cam (the cam follower plates below the fuel pump are appx 3" tall on small cam and appx 6" tall on big cam), then you can set the AFC valve to give more fuel, assuming it is working right to begin with.

Remove the throttle arm from the throttle shaft sticking out of the pump. Pull back the top of the riveted on aliminum plate that surrounds the throttle shaft, assuming it is not already gone. There you will see an allen head screw with a lock nut on it. Loosen up the lock nut and turn the screw out about two rounds.

This will give much faster throttle response and will cause smoke when changing gears. If someone has been messing with the pump they could have turned the screw all the way in, and this can cause your problem.

Do not go too much with the screw or you will cause too much black smoke and rattle upon acceleration, plus it makes the throttle touchy, which can make smooth gear changes harder.

Once you get the other problem straightened out you can play with the settings to get the throttle response you want.

The big cam 300 has an aftercooler like the 350 and 400. A 290 has a three legged intake with no aftercooler. This intake looks like the old 250 intake. A small cam engine will have the smaller cam followers and will have the old style pump that may or may not have an external AFC valve mounted under the aftercooler, plus the cover surrounding the throttle shaft will be held on with a large snap ring. No need to take this off, for there is nothing there you can do to help yourself.

The newer big cam pump will have the letters PT stamped into most, if not all of them.

Change the AFC diaphragm first. It is cheapest and quickest, and most likely to be your problem, unless you have not changed the fuel filters, which should have been the first thing you did.

 

Hey Medicine man, those were good old engines, hell I go back to the old 220s and 318s, and that is like resurrecting the dead. Hey don’t be too hard on the young technicians they just haven’t had to opportunity to work on a lot of the old engines. The new ones are so much more efficient, fuel economy, reliability, and power is just so much better. Once we went to ECM controlled fuel systems and injectors the whole world changed, and it isn’t ever going to go backwards. My wrenching days are done, even sold most of my tools. So I’m going to take the time to learn to be a real driver and run OTR for a while and see something other than the inside of a shop. But thanks for the complement.

 

+1 - a leak down test will tell you a lot right there. If the rings are shot or it needs to be re-sleeved (happens alot on the BC's), you aren't going to be getting any power. Does it smoke like a bingo player?

 

I hope that link to the Low Buck fuel rate site worked out. I havent worked on a Big cam....yet, but that's my site. It told me there was a link from this page, so I thought I might stop in to say hi. Hope it's not missing anything, besides pictures. I can get some if I had a willing participant near me.