Hello All:

         Is there any reason that I can not satisfactorily use a RC carb for Sport/Stunt flying? if one rigs the RC carb to be open at all times, would this not work well?

         I have several HP .40 engines that came with custom nva and venturm.  The holes in the venturm are much too large to draw fuel.  I could block off a bit of the hole in the venturi on each, but I also have the original RC carbs.

      That generally works OK. The one minor flaw is that almost all of them tend to have small shifts in the RPM as something inside the carb shifts slightly and either leaks air, changes the mixture, or changes the opening. This seems to matter a bit to 4-strokes and people themselves semi-crazy trying to figure out what it was and fix it  until they decided to ignore the "super-expert 4-stroke advice" they got from the promoters/salesmen and just replaced it with a venturi. On 2-strokes you can sometimes still detect the effect, but it seems to be almost negligible in most cases I have seen. This would be a bit of an issue for competition but for sport flying, no issue.

        Be sure and adjust the carb over the full range of openings, just like it says in the instructions. Then either use the idle stop and a spring, or a clevis and spring, or something, to make it so you can adjust the throttle opening from wide open to maybe 75% to start with. Then set the speed with the throttle position rather than the needle. This is like having a variable-sized CL venturi, which makes much more sense for speed control than a fixed venturi and setting the mixture to adjust the speed.

    Brett