If its fully mechanical, not a peec like bryan asked then pop the peanut cover off, back out both screws a 1/2 turn and then turn the AFC in one turn. Watch the pyro and boost. I would do this AFTER making it run to orignal specs from up above. After setting the valves, and checking the advance. Also the boys had a bull hauler on the dyno the other day that was "low" on power. It was a 425 3406 B dynoed at 450 at the rear tires. Found a governor spring weak, installed the correct new one and it was putting down 500 at the back tires. It too was an old B model. Another old black Marmon came in the other day puttin 525 at the back tires with a B model 3406. It had a differnt charger on it though.
Another approach is to crimp the AFC line off and take the guts out of the AFC housing. This will make good response, but lots of smoke.
I agree that new injectors will cause a power loss. They are notorious for "growing" with age.
I did the above tweaks to a buddy's cab over pete 84 model. It has passed many new trucks hauling around a large tile machine on interstate 80 here in Iowa! Had a couple of guys try and run with him the other day and they couldn't. Not too bad for an old 400 horse 3406 JWAC with close to a million miles on it.
Last edited by MMiller; 03-27-2005 at 09:35 PM.
1993, 250, 4x4, 5sp, 3.54, HX40,4" exhaust, "adjusted" pump, Bosch 185s,
1985 Crew Cab D350, Cummins, auto-eventually to be a built 47rh to go with the dana 80.