I have a question for someone who is knowledgeable of the above titled issues. I have an OS FT-120 twin-cylinder engine. This particular engine has the carb positioned horizontally, facing forward and on my plane is open directly to the airstream through the propeller. Here is a Tower Hobbies picture of the FT-160 engine which is identical with just a bit more displacement, http://www3.towerhobbies.com/cgi-bin...?&I=LXBY68&P=7 . This carb is strictly the venturi type. It has no pressure line from the exhaust to the tank and no pump. It draws fuel simply by some gravity(when the tank is full) and mostly suction(carb venturi). The tank height is centered on the carb intake. Now the question??? When in flight, since the carb is facing forward directly into the airstream, will the mixture go more lean or rich as the airspeed is increased? Or will there be no effect?