Dan I believe that in all cases, if you do not prevent the carb from closing, the throttle plate on ALL carbs will get sucked shut or sucked open, depending on which way the bias is made in the throttle plate. Most throttle plates are made with a slight bias towards the bottom, or closing direction, so that the engine will suck the throttle plate against the throttle stop screw allowing it to hold an idle consistently. If not you would have to actually move it back to idle, or any other position always. The Lycomings I flew would suck the throttle shut gradually while running if some amount of friction lock was not used. We would always set it so that there was just enough tension to hold the throttle in place but allow for changes to be made if needed or desired.
Be glad you do not have my carb; I have to ADD a spring to counter the throttle return spring so that mine will stay put where I open it to or it will behave like it does in the car and return to idle whenever I am not holding the throttle! LOL I will also add some friction at the throttle quadrant for holding it in one place, but allowing for adjustments... Colin Rainey brokerpilot9...@earthlink.net EarthLink Revolves Around You.
