[Sandy]

I have managed to get away with the stock 5/16 fuel line and pickup feeding a mild 454 with maybe up to 450 sea level hp (7.5 psi fuel pressure). Shifting at 5500 and 6000 through the traps.

Everyone says to go bigger, some say 3/8 some say 1/2 inch.

Considering the relatively small flow capacity and size of the needle/float and jet sizes in the holley 750 carb what is really required ?

I can see going to 3/8 as realistic, but 1/2 inch ???

What about at a higher horsepower level say up to 550 or 600 ? Any need for larger fuel line ?

 

[Milan]

I have always wondered the same thing. I am skeptical...but, I will say this I am in the process of swapping in 1/2" plumbing vs the 3/8 plumbing in my camaro as the car has a bottleneck somewhere as it stops pulling as hard somewhere above 5500 (I will post my findings).
I have NEVER found ANY conclusive evidence to support one size VS another. Its always been opinion. I looked for before and after info and found nothing. From what I have seen 3/8 will support at least 500 HP.

Milan

 

[mr 4 speed]

Sandy,what kind of fuel pump do you have?

 

[dave_silva]

On our race cars with 450+ HP we use an-8 for regular fuel and an-10 for alcohol (uses almost double). That should be 1/2 and 5/8".

 

[dave_silva]

On our race cars with 450+ HP we use an-8 for regular fuel and an-10 for alcohol (you use almost double the fuel with Alky). That should be 1/2 and 5/8".

 

[Sandy]

Using Holley blue (the noisy one!) with pressure regulator, no return line

 

[EMcIllece]

Question. Ever heard of too big of a fuel system? I haven't.
You have plenty of fuel pump, but not enough line. Put 1/2" at the least, which is AN-8.