Fuel plumbing for an FE

[HSSS427]

My understanding is that it's all about where the constraint is in the system so you want the smallest diameter line at the carb, with everything in "front" of that going up one size at each major connection back toward the tank. Seems having any -6 lines in the flow before the -10 is going to limit you to the -6 flow rate. But with 2 -6 lines feeding one -10 line, then it's hard to say - would that be the equivalent of a -12 feeding a -10 and then into a -6? Also, putting the regulator near the carb makes sense as that's where you need the pressure to be regulated - going into the float bowls. And won't do you any good for the lines to the carb to be any bigger than the inlets. As for how much difference in flow, there's too much science in that answer for me :-)

[Anthony]

Originally Posted by HSSS427

But with 2 -6 lines feeding one -10 line, then it's hard to say - would that be the equivalent of a -12 feeding a -10 and then into a -6?

If I remember correctly, I believe the AN stands for Army-Navy , and the number is the diameter of the tube, such that you take the number / 16, and that's the diameter in inches. 2 6-AN's do not equal 1 12-AN line, the 12-AN line will flow more. Going from cross sectional area alone, I would think 2 6-AN's will flow alittle more than one 8-AN, but not as much as 1 10-AN, and definitely not as much as one 12-AN, which may be equal to about 4 6-AN lines.

My guess is that since cross sectional area is a function of radius (diameter) squared, you square the number to get the relative cross sectional area, so a 6-AN line would have a relative area of 36, 8-AN would have 64, 10-AN would be 100, and a 12-AN would be 144.

[Carnut427]

oooooooops

[Carnut427]

Originally Posted by HSSS427

...Seems having any -6 lines in the flow before the -10 is going to limit you to the -6 flow rate...

The -6 lines each feed a separate pump, -6 lines come from each pump to a "Y" where they meet and go into a -10 from there. Each pump on my system gets fuel from a different side of the fuel tank; when I raced the car it would starve for fuel on the corners, this solved that problem. My car runs on two pumps 99% of the time, so they each get fed by and feed the -6 line until they can meet at a convenient spot and go into the -10.
My regulator is beside the two carbs, with a 3/8" (-6) line going to each carb.

Dan