If turn it in it moves the afc arm foward and makes more smoke back it off and it will smoke less and i dont think it really gives you much power i think its mainly for tuning the pump not so much for power.

yea its just tuning, adjusting it in allows the governor to travel further without any boost,

The smoke screw won't affect the rail, it merely preloads the diaphram in the pre-boost fuel circuit, once on boost the AFC and ALL of it's components are out of the loop. Okay not completely....it WILL hinder gov arm full travel if you have the extended rack plug, but we won't go into that yet. Preloading the smoke screw moves the AFC foot towards the front of the motor as said above and allows more pre-boost fuel. So does moving the position of the AFC relative to the pump itself via it's mounting screws. The star wheel is the opposing force to the diaphram's movement aka the pre-boost curve. The looser the star wheel, the quicker the AFC will allow power circuit fuel....or black smoke id that's what tickles your fancy. It's not the true way to tune, but it makes for a good show. Recurving with springs and fine tuning all 3 adjustments is the best way to tune, but most just wanna gut it and make smoke....the turbo will eventually catch up LOL. Anyway, turn the top of the starwheel towards the engine to loosen the pre-boost curve.

Chris

Exactly......Very well said

you pretty much covered it all:tu::c:

How much will it raise my egt if all the way screwed in? I have no pyrometer and cant afford one after being laid off
:scare2:

it wont because you arnt giving your engine any more fuel just changing when you get it. overall EGT raise should be unnoticable.

Thanks thats all i will do for now untill i get me a pyrometer i guss:c:

My truck has 90 hp sticks, timing advance of 16*. just got my pump adjusted, and the ruck works great, it doesn't smoke much, but when it hits torque lock in 3rd you can see some smoke. If I turn back the smoke screw it should stop smoking, and not affect the pump, or any adjustments for fuel delivery?

Corb

:c: