Replacing Fuel Line

74DartSwinger360 said
5/16 is factrory slant 6 line
3/8 is factory v8 line
My 74 has the 5/16 and is runnin a 360 no oproblems but will eventually change to 3/8 stainless

Not true, all stock small blocks, including the 340 and 360, used 5/16. Not sure of any stock V8s that used 3/8 (maybe some Hemi cars).

If you upgrade to 3/8 and want to realize any improved flow you will need to swap out the fuel tank pick up assembly and get a fuel pump with 3/8 inlet and outlet and 3/8 (or -6) from pump to carb.

straightlinespeed said
I have used Inline tube when I built my Jeep. I was thinking they only sold complete line sets. They do have great quality and fit great.

Is that for sure a vent line or is it the return line from the original carb? Im unsure what that line really does? It was capped when I bought the car.

Follow the vent line back to the tank and remove the ruber hose that connects it to the tank. If that nipple on the tank has a very small ID (like 1/16" or smaller) it'a a vent line. My 72 had the vent line, 71's may have also had them. If it's a vent do not plug it! Your tank needs a vent.