Return line fuel restriction?

Hallzy said

I've been doing some reading and cannot seem to find a straight answer..if there is one.
Plumbing in my fuel system: from the tank I have 3/8 to 8an through 100 micron filter holley black pump 140gph through regulator then 35 micron filter to carb. On the return is where my question lies I have 8an back to the tank but the return at the tank steps all the way down to 1/4" is this restriction going to cause problems?? This will be feeding a 500" 643hp engine.
Thanks in advance for your input and help.

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The only truly correct way to do this is to run the same size lines, fittings, everything from and to the tank. -6AN is pretty adequate for almost anything under 600 HP. Pickup in the tank if you can using an in-tank pump. Otherwise use an external pump near the tank, mounted lower than the pickup so it siphons naturally. Run that line to a good filter, near the engine. Then the filter output goes to an adjustable bypass fuel regulator. One (or two) output lines from the regulator go to the carb or EFI. Then you run a line from the return port of the regulator back to the tank. I have run this setup with both EFI and with a carburetor and it works great. I'm using a Tanks, Inc. 60 psi pump in the tank, and a Aeromotive Universal Bypass Regulator #13301, which is one of a very few that can be run with a carb or EFI (3 TO 65 psi). This is a key component to building a good reliable system, so don't buy a cheap regulator!