ORIGINAL: jetmech05
The reason for two clunks.....one clunked line to the carb of course....the other clunked line is for de-fueling at the end of the day. and goes to the fill line.....you don't have to have a clunk on the fill line...but if you don't then you have to tilt the tail of your airplane up to de-fuel the tank
All my three line tanks have two clunks too, even my big tanks for my gas engines. I don't know anyone that sets up a three line any other way. I have never seen them tangle and have a fuel draw problem but I have had a few get stuck in the front of the tank after a sudden stop. I try to avoid the sudden stops though but they can happen.