Loop guy here...

The loop just provides an air gap preventing a siphon if the carb is below the spray-bar. It is useful if you leave the plane with the tank full for a few minutes to prevent the engine from flooding and the fuel from being siphoned out. Just make sure the fuel line runs above the spray-bar and the carb somewhere between the two. It usually is not necessary to do it intentionally since most installations will have enough slope in the line to keep fuel from running....'down-hill'.

Other loops include hula, fruit, loopty and those big ***** earrings the bad girls wore in college...um so I heard.

Good Luck!!

OOPS did'nt mean to confuse you...loop goes between tank and carb, not spray-bar and carb...I had my definitions wrong, apparently....always thought the spray-bar was the tank outlet.

Later!!