This tapered screw regulates the amount of air that bypasses the throttle plate on Weber IDF carburetors. It is located at the base of the IDF body next to the idle mixture screw. The air bypass screw gets locked in place using the Weber IDF Air Bypass Jam Nut, Part No. 1586-68 (sold separately).
Sold individually. Two screws are required per carburetor.
Note: Fits genuine Weber (made in Italy or made in Spain) carburetors only! Does not fit most copies, Asian knock-offs, or work-alikes.