I was shopping for AN fittings today and I called a vendor who suggested I use 6an throughout my fuel system. I have an accel single plane with rails I'll be putting onto my '94 shortly. Now if I remember correctly, the factory feed line is 3/8 and the return is 5/16...basically, 8an and 6an. I dont feel like holding myself back in the future when I put in a bigger engine, but will there be any forseeable problems using larger supply lines on a 383? I dont see the point in running a 6an on both sides and bottlenecking one of the lines.

I want to run 3/8(8an) up to the back of the drivers side rail, the same at the crossover, then 5/16(6an) through the regulator, out the bypass on the bottom back to the tank. Regulator is an accel high pressure (30-100 psi) adjustable universal unit. Should I do this so I dont have to redo it in the future or will there be problems?

 

3/8" = 0.375" = -6AN tubing nominal diameter (0.3438 actual inside diameter)

The AN "#" is roughly the tube diameter in 1/16's of an inch.... -6AN = 6/16 = 3/8, -8AN = 8/16 = 1/2".

http://www.russellperformance.com/te...nualorigin.htm

I run 800 flywheel HP through a -6AN feed line, splitting in a "Y" at -6AN into the rear of each rail, then a single -6AN return line from the diagonal cross-over pipe back to a Weldon AFPR under the cowl, and then on back to the tank. If you plan to go higher than 800HP, using -8AN for the supply line at least would make sense. The shop that installed my fuel system made a very strong case for not going too large on the fuel lines.