Ernie and Scar, Thanks for the info.

Ernie-I didn't think to shut off the throttle first. I will try that next time. The fuel feed (to carb), muffler vent and auxilliary line (again, presumably for a fuel probe) are all at about the same level. They form a triangle pattern as they all go into the TOP of the tank, although, I believe the fuel-to-carb line is the lowest of the three which might explain the carb overflowing first.

Scar- It is a cowled engine, and I am new to RCs, but not mechanically inept (I built many finicky british motorcyles and tuned many of their carbs). I'm pretty sure that I have my controls well sorted out but will seek assistance when I go to fly; frankly, I won't even be flying it since I've never flown before, so I will enlist the help of an expert to get it off the ground.

I don't think I am having any significant fuel line issues, I suspect it is as Ernie said: If the vent line is at the top, then you would expect the carb line to overflow first, right?

I do appreciate all your guys' help. Many thanks.