I Post this question only after searching the Forum and not finding information on exactally the combination of engine and injection pump that I am dealing with. I have a 1976 R model Mack with a ENDTB675 engine rated at 235 hp. It has a United Technology "Mack" Injection pump. Pump # is APE 6BB110T6648A1. This truck has a 5 speed Single stick tranny. I would like to get annother 10-15% out of this engine. It sat for almost 7 years prior to being put back on the road early last year. We obviously have replaced fuel filters ( many times untill we actually washed the rusted steel fuel tanks out) It tops out at 2200RPM under light load, which is fine, and runs quite smoothly, but I can't mantain 50mph on a moderate hill with an empty 26' City aluminum dump And it is VERY slow accelerating up through 4th and 5th gears. This injection pump has the pressed steel cover on the govenor that is at a 45 degree angle sloping towards the rear of the pump held on by four 1/4 inch bolts, and the round heavy steel cap on the rear end of the pump also held in place by four 1/4 inch bolts that has the heavy spring inside of it. If the "puff eliminator" is the cylinderlike extension on the front of the pump it is not hooked up, as there are NO lines from the intake manifold to the injection pump, but there are suspiciously similar 1/8" brass plugs on both the end of this cylinder and on one of the small ports in the intake manifold. I get NO smoke at full throttle, and have never had the engine temp over 200 on a VERY hot day. Mostly the engine temp stays at 180-185. The throttle lever on the pump is new, and the fuel stop lever gets put into full open when the dash knob is put all the way in. The foot throttle when fully depressed fully extends the throttle lever into the "spring over" position. I don't have a pyrometer on this truck yet, but am thinking that I will if I can succesfully turn it up or make it work properly. I have pictures of this pump that I can send to soon. Matt
