I have a '84 6.2n/a. Trying to make it as efficient as possible(best HP with corresponding MPG). Have installed a J code intake, K&N filter and a free flowing exhaust(2.5" into a 3" thru an Ultra Flow). With the extra breathing this engine is doing should i be increasing fuel a little? Can you run a N/A diesel too lean by adding this extra air without the proper fuel increase as well? I know diesels run extremely lean mixtures and high pressures and temperatures but where is the limit? I don't have a pyro but could probably borrow a scope. If it needs more fuel, how do you go about it? Turning the pump on its mount simply advances or retards the fuel impulse does it not? Is there an internal adjustment on the pump that adds fuel? I realize most fuel adjustments are going to hurt mileage performance so i'm wondering where the best balance would be? Any help would be appreciated. Thanx

A diesel can't run too lean. You have already added some J engine mods, now to see the full benefit you will need to turn up the pump. This requires removing the top of the injection pump, removing the governor assembly, removing rear allen head bolt/governor pin, rotating engine by hand until the fuel ramp set screw is visible. This requires very small movements of the crankshaft while watching down through the top of the pump with a flash light. Turning the screw clockwise will result in more fuel. Give it 1/4 turn if you want to go fast, 1/8 turn if you want to try it in smaller increments. Then give the injection pump about 1/16 inch of advance and call it good.:grd: