ORIGINAL: trainer25
ok so the long needle on the left side (cockpit view) is the hsn, the horizontal screw on the right is the idle speed screw, so what is the 3rd screw for? believe it sits on top of the carb going down
That is a throttle stop screw. Completely useless on airplanes. Open that up to the point the caburetor barrel will close all the way. Then set your control servo so at the lowest throttle setting with the trim up all the way will leave about 1mm open throttle. Then you can pull the throttle trim down to close it the rest of the way and shut the engine down by choking off the air supply.