New fuel line: 6AN or 8AN inlet fitting

[69 Mach I]

I have a 650 cfm with vac. secondaries for the moment. It is going back to Summit to be exchanged for a 700 cfm double pumper (mechanical secondaries - yeah, I know, it is redundant to say that). In the mean time, I need a new fuel line. I am looking at both of Aeropquip and Earls Performance and have to choose between 6AN fittings and 8AN fittings. Which one do I want, keeping in mind I am upping to a bigger carb in the near future?

[DonC]

Find the smallest diameter line in your system and make any connections above and below that point one step larger.
-6AN is roughly equivialent to 3/8" dia and -8AN is roughly equivalent to 1/2" dia. so if your hard line is 3/8" use -8 connections above and below it. You can use -6 without "IN GENERAL" seeing any degredation in flow volume but a properly engineered system provides greater capacity above and below the point of highest restriction.
DonC

[DAVID GAGNARD]

I run 8an from the tank to the fuel pump and 6an from the pump to the carb (650 dp) and have had no problems,also using a Carter mechanical pump,I think it is rated at 6psi and 120gpm flow...........

David

[relaxinrob]

I'm running 10 AN from the tank to the fuel rails and 6 AN as the return.......8 AN should be plenty for your app.

[sharpe 1]

I have a 750 vac secondary holley with 8an setup form aeroquip work fine.