Help!! Fuel Line size recommendation

[Pman1961]

Okay, so one part of my information was incorrect. I have a Holley 12-125 125 gph electric fuel pump with maximum pressure of 7psi. So no external regulator was required. These pumps use 3/8" npt fittings. Without a fitting in front of me to check inside diameter will this be okay using 3/8" npt female with 8an male ends or do we create a restriction? For now so I can get rolling is to plumb from the output of the pump to the carb with 8an steel braided hose and replace my dual feed carb line with a 8an in lieu of the 6an presently on the motor.

[lippy]

I have a -10 pickup with all -8 lines except from the front regulator to the carb (x2), which are -6.

[RICK LAKE]

Pman1961 I race 98% track and run 2 systems of pumps, filters and check valves. I only run 1 pump at a time unless needed. Backup plan.
#8 or #10 line is the best way to go. better to have too much supply than running lean on long runs. Wrapping and or shielding the lines from tank to the motor is also needed. Clamp the lines to the frame every 12" to stop vibrations.
Rubber hose keep to minium because of the ethohol in the gas eats rubber over time from the inside out. Takes about 8-10 years for failure, repaired twice between fuel outlets and fuel pumps.
I would recommend a pressure regulator of 6 psi with a #6 return line to the tank. This will pervent vapor lock when racing.
Put an electric fuel pump as close to the fuel cell or tank as possible. Some of these pumps don't have good vacuum. If you are going to race, get a fuel cell that is SEFI aproved.
Better to have more than is needed, then not enought when running.
Also look into running marine 4" fans under the hood to help remove hot air in the motor bay. Simple hookup with 2 plates to locate fans and blow air out louvers on front fenders. It helps alot and knocks down the temp about 20-30 degrees. Good luck. Rick L.