Originally Posted by earlwb
Normally one does not use muffler pressure with a gasoline engine setup. I suggest using a three line setup for the fuel tank, one line is the fuel line, one line is for the vent and the third line is for refueling and defueling the fuel tank. I use a large loop or two for the vent line so that the fuel doesn't siphon out if the plane is inverted.
The gasoline engines use a pump carburetor so they do not need muffler pressure. You can pretty much place the fuel tank any place inside of the airplane as the pump in the carb draws the fuel for the engine and provides the fuel at a constant pressure via the fuel regulator to the engine.
I don't understand - How do loops in the vent stop the tank siphoning out when inverted?