Fuel plumbing for an FE

[HSSS427]

OK, but to Anthony's point, is the flow from the combination of the two -6 lines greater than, or less than the flow potential of the single -10 line. If it's less, then you may want to change those -6 lines to something larger to remove the "constraint" and maximize flow up to the carb. So, answer may be: change the -6 lines to something bigger and move the regulator up to the carb end of the -10 line.

Of course the simpler answer is to actually figure out the flow rate you're getting and determine if that is indeed sufficient before making any changes. Could spend a lot of time and money based on theory when in fact there isn't an issue - which I always find myself doing despite this advice I think I have some weird need to have more projects to do on the car vs just going and driving it

[Carnut427]

Originally Posted by HSSS427

OK, but to Anthony's point, is the flow from the combination of the two -6 lines greater than, or less than the flow potential of the single -10 line. If it's less, then you may want to change those -6 lines to something larger to remove the "constraint" and maximize flow up to the carb. So, answer may be: change the -6 lines to something bigger and move the regulator up to the carb end of the -10 line.

This has gotten complicated, sorry I didn't make myself clear: I posted to help shelby racer; my car runs fine. Let's change my -6 and -10 designations to their fractional equivalents. I have two separate pumps from the tank, each feeding 3/8" diameter lines, which converge into one 1/2" diameter line. My two 3/8" lines are roughly the equivalent of one 3/4" line, making the 1/2" line the restriction, but it flows plenty for my engine. From the regulator I again have two 3/8" diameter lines, one going to each carb.

Originally Posted by HSSS427

I think I have some weird need to have more projects to do on the car vs just going and driving it

Me too. It's like having my very own personal black hole, sucking money out of my wallet. However, I have no desire (or enough courage? ) to stop. I'm always looking at "improvements" or merely changes. It's truly a disease with no known cure.

[Anthony]

Originally Posted by Carnut427

Let's change my -6 and -10 designations to their fractional equivalents. I have two separate pumps from the tank, each feeding 3/8" diameter lines, which converge into one 1/2" diameter line. My two 3/8" lines are roughly the equivalent of one 3/4" line, making the 1/2" line the restriction,

two 3/8 lines do not equal one 3/4 line.

[Carnut427]

Originally Posted by Anthony

two 3/8 lines do not equal one 3/4 line.

You're right, there is more wall area on the two 3/8" lines causing more restriciton, so I said they are roughly equivalent to one 3/4" line.

Your input is appreciated, Anthony. You've got a lot of knowledge stored in that cranium of yours.

Dan

[scottj]

Compared to 1 -12 line, 2 -06 lines are roughly half.

2 -06 lines are roughly 74% of 1 -10 line and roughly 23% more than 1 -08 line.

-06 = .344 dia
-08 = .438
-10 = .562
-12 = .688

[Anthony]

Originally Posted by Carnut427

there is more wall area on the two 3/8" lines causing more restriciton, so I said they are roughly equivalent to one 3/4" line.

The major factor for flow resistance is cross sectional area, which is a function of the square of the radius (diameter). Wall area is a minor factor, and doesn't really only come into play if you have two conduits with the same cross sectional area even though one has more wall circumference. The one with the greater wall circumference will have slightly higher resistance to flow due to higher boundry layer-flow interface, and therefore flow slightly less. The greater wall circumference effect would only be very significant if the cross sectional area is really small to begin with, or there is a very large discrepency between the two conduits minimum diameter or wall circumference.

[Anthony]

Originally Posted by HSSS427

OK, but to Anthony's point, is the flow from the combination of the two -6 lines greater than, or less than the flow potential of the single -10 line. If it's less, then you may want to change those -6 lines to something larger to remove the "constraint" and maximize flow up to the carb. So, answer may be: change the -6 lines to something bigger and move the regulator up to the carb end of the -10 line.

If your pumps are not resticted by 6AN lines, then changing to anything bigger wouldn't matter. I would think the 10AN line should still have less resistance than the two 6AN lines combined, and, again, if the pumps are not restricted, then there's no point in upsizing the lines from the pump.