ORIGINAL: GeeBeeJim
Y'all don't want to get that servo too close to the engine, or else you are going to get ignition pulses induced back into your receivers circuitry. It's always a good idea to mount the throtle servo well in back of the firewall, and connect it to your Carb with a non conductive pushrod. You can get away with it some of the time, but not all of the time. There is no big deal about using proper bellcranks to do the job of linking the servo to the Carb.
I've seen the use of ferrite rings to reduce interference work very well (as least on glow motors) so would that be a feasible way to minimise interference coming from a throttle servo?
At this point I've mocked a dubro ball link to the throttle arm. The pushrod then extends near vertical (within the ball links limits) and can connect to a servo mounted approx 2 inches below the carb. The servo would be mounted off the firewall in a wooden block and thus not have any direct connection with the motor.