Which size sending unit to use with low pressure fuel pumpo

[mattp.426]

I have a 1971 Challenger with a mild small block, and I was preparing to finish off the fuel system, but I'm not sure which size of fuel line I should use, and if I should add a return line. The engine doesn't have the piece on the cam for a mechanical pump, so I have a low pressure Spectra unit (SP1130, only about 55.7 - 65.0 gph and 4 - 7 psi). Is there any advantage to switching to a 1/2" line, or adding a return with this pump?

 

[mrmopar340]

I use a 120gph 7.5 psi Carter Super Strip pump with no return line. 3/8 line and over 400 on ground from a 340 and no problems on it.

 

[cuda joe]

with a return line you have less chance of vapor lock