I just recently bought a '77 W900A with a NTC-300 Big Cam III and a 10 speed to haul grain with. Weighing 80,000 lbs., it will barely do 58 mph. Everyone I've talked to said it should at least be running the speed limit with no problem. Is there any way to bump up the pump? It has a new fuel filter and the air filters are clean. I have to haul grain transfers tomorrow and would like to turn this thing up before then. If you know what I need, please let me know.

Thanks,
CJ

 

I remember in the 80's lookin at a big cam Cummins and I saw a seal on the injection pump......................I would be fer brakin the seal and dialin some **** up in there

 

Dude...ok

 

Just out of curiosity, what rpm's are you turning at 58?
Is it lack of power, or just no more rpm to be had?

 

if it has always been down on power, they probably had the fuel pump turned down. there is some who think its better to turn them down. imo i would swing by a shop and have them turn up the pump and see how it does

 

It's running 1600 rpm at 58, empty at 70 mph it's at 1900 rpm. I just bought the truck, so I'm not sure if it's always been low on power.

 

the power band is 1800-2200 so there is some room to grow there for ya

 

So what would redline rpm's be on this thing? I was told not to rev it any tighter than 2,100 rpm. I talked to the guy at the injector pump shop and he had me tear down the pump over the phone to check the arenoid valve and diaphram. It all looked ok, so tonight I'm replacing all the fuel lines. He said if they're old they could be collapsed on the inside.

 

max RPM is 2250

 

I've always been a fan of max fuel & max rpm