ORIGINAL: Konrad

All auto mixture type carbs with an air bleed idle adjustment should be adjusted with the air bleed closed. If and only if there is hesitation or an adjustment is needed at idle for tank placement should the air bleed be opened. The Fox Easy Adjust carb is an auto mixture type carb but with a fixed metering slot and position. There is no cross talk with the Easy Adjust carb at full throttle.

Not that Fox has ever used an air bleed type carb but they too should be set with the air bleed shut. And if possible the tank placement be adjusted to gain the desirable idle mixture. Failing that the air bleed should be opened to get the best engine response. Remember that any air that is bleed is not contributing to the fuel draw from the tank. With the low air flow at idle the engine need all the help it can get to bring the fuel to the engine. I can't stress enough the need for proper tank placement no matter the engine brand, carb type or plane used. Most ARF trainers place the fuel tank too low.

Opening up the air bleed limits (deteriorate) the engine's ability to draw fuel fuel from the tank. This is why the Fox line of engine is so superior to some of the popular asian brand entry level engines. As all Fox RC engine come with an auto mixture carb of some sort, even the little Fox 0.15 BB R/C. They all draw fuel better than any true air bleed carb at idle. This alone is worth the extra effort some FOXs need in giving them 20 minutes of your time and fuel to break them in. There are a lot of other benefits to the Fox but that would be called piling on by some .

All the best,
Konrad