I will probably get beat on, but I think the best thing is a Kwik-fill fueling valve. Just put in the line from clunk to carb. When you plug in the fuel probe, it cuts off the line to the carb. Works great for fillling and emptying both. Now, I know lots of folks have problems using these valves, citing air leaks, stopages, ect. With a good fuel fillter, most problems can be eliminated. Best thing is to always check your system prior to takeoff. Use, it, but don't trust it. Always check!!