I bought a new gas tank and sending unit.my original sending has 2 lines,one 3/8 line (supply) and one 5/16 line (vent).when I got my new sending unit,it has only one 3/8 line and no vent.the motor is far from original so I don't have anything running to the smaller line anyway,but will this be a problem for the tank or will it vent through the cap,
thanks for any help
dave

The tank will vent through the fill cap. The smaller fuel line was the overflow return from the 3-nippled gas filter in front of the engine.

The OE filter had inlet, outlet to the carb, and a return to the tank. This set-up aided in the prevention of vapor lock. The filter was/is mounted between the fuel pump and carb.