350 cummins question

Theres a little plastic ball in the end of the shaft the throttle arm mounts on. You can dig that little ball out with an o-ring pick and turn the screw out behind it all the way and gain 10-20 lbs fuel pressure maybe more depending on how it was set initally. Thats a fine adjustment used when the pump is calibrated on the bench.

 

chang the button and shim in pump, you will get the power you want

 

Use an experienced Big Cam mechanic.Let him work on the pump-changing springs and button,and he can make other minor adjustments.If your engine is in decent condition you should notice a big improvement for a couple hundred bucks.

 

Small cam? I think 1975 or 1976 was the last year Cummins made a small cam engine. If that is true, then that truck has either had an older engine put in it, or it is a glider kit.

I do know the first Big Cam Cummins came out in 1976, and the Big Cam II in 1979.

 

The point I am making is the small cam motor has not been made since the mid 70's.

 

Check first to make sure it is a small cam. If it is not, then find out which Big Cam it is from the tag on the accy drive housing or see if it is stamped in the side of the block somewhere.

As far as the small cam engines go, they can be rebuilt many times. Most all of the NH/NTC engines will leak water around the heads.

A small cam will not have the torque of a big cam engine, not will it get as much fuel mileage. 4 mpg to 4.9 mpg is most common.

Things that can happen to them is stress cracks around the head bolts, counter bore around the top of liners.

Something that can happen to all engines is for the liners to get pin holes from not having treated antifreeze in the engine, and liner packing (o-rings and seals) failing from many miles of use, or from sitting too many years with no use.

Listen for knocks, look at the oil pressure, check for excessive blow by from breather pipe. A good way to check for worn main bearings is to get the engine hot and drive it on level road. Choose any gear, 7th or 8th may be best, have the truck in a slight pull and check the oil pressure.

Next let off the fuel so the truck is holding back while watching the oil pressure gauge. Any increase of more that a couple pounds means the bearings are worn.

Do this test at around 1900 RPM.