I stole the text here from another website, but i think he also stole it from yet another site....
I added photos, although i did not take any when i actually had the jamb nut out of the IP.
"To the rear of the pump on the top is 2 different allen plugs. The bigger one is the fuel rate, and the smaller is the star wheel, or pre-boost smoke adjustment.
To do the fuel you take off the plug with either a 3/8" or 10 mm allen wrench. Now tie up the fuel shutoff sol. or pull cable in the run position and you will see the adjustment screw. You may need to put a brick or such on the accelerator to keep the screw in the right spot under the hole. Break the jamb nut loose with a 3/8" or 10 mm deep socket and loosen the screw all the way. At this point it will be loose in the rack, but not fall in. Take some needle nose pliers and carefully remove the screw. Run the nut so there's 3-5 threads left on the screw(away from the head). Now (again-carefully) put the screw back in and tighten it with a regular slotted screwdriver up to the jamb nut. Then a good snug on the jamb nut and it's done. If you drop the screw inside the pump you can retrieve it easily with a pencil type magnet. Untie the shutdown sol. and remove the accelerator weight tool. Under the smaller allen plug is the star wheel. Take the plug off with either a 5/16" or 8mm allen wrench. Spin the star wheel towards the front of the pump(rotate towards the pass side) to increase low end power(smoke)and away for less low end smoke. The governor spring adjustments are the same as the newer 466's described above."
i labeled some more IP photo's if you want to see them