[Ikestaa]

AN line is numbered in 16ths of an inch. So, -3 is 3/16 and -4 is 4/16. This is the ID of the tube. All of the fittings are different sizes for different sized line. You can certainly use -4, but it is not necessary to have a line that flows that much, since it is really not flowing anything at all once the motor is started. I'll make a list of every part we used if you want to use it.

-3 Speed Flex line (not sure on length)
-3 straight hose ends (2)
-3 to gauge adaptor (1)
-3 to 1/8NPT adaptor (1)
Fire Guard shielding (again, not sure on length)