Fuel Line Size?

[LuckyHenriksen]

I am trying to sort out a new fuel system, and am having trouble. I have found a Holley pump, which will work great for my application, and it says it has 3/8 hose inlets. When I try to find fuel line it is all measured as AN sizes. How do AN and NPT sizes compare? Will one be the equivalent of a 3/8 connection?

[Shane]

-6 AN = 3/8"

Take the AN size and put it over 16 and reduce the fraction to get the -AN TUBING SIZE ... NOT the thread size.

-AN and NPT have absolutely nothing to do with one another. NPT is the tapered thread end that threads into the fuel pump housing and the 6 -AN is the end that is going OUT and holds the 3/8" (-6 AN) tubing.

4/16 = 1/4"
6/16 = 3/8"
8/16 = 1/2"
10/16 = 5/8"

Here's a link that might help ya too ... AN Tube & Thread Size Chart

[LuckyHenriksen]

Sweet thanks Shane, just what I needed

[LuckyHenriksen]

Oh and can someone explain what AN and NPT stand for? And I want to run line from my tank to my pump to my regulator to my carb, do I need to buy several different pieces or can I buy one long piece and cut it to fit, then re-attach the fittings? Sorry for the newb questions, but this is the first time I have messed with this stuff.

[Shane]

AN = Army/Air Force & Navy

NPT = National Pipe Thread

hope this helps ....

[LuckyHenriksen]

It does, thanks!

[68Stepbed]

You also need to watch out for inverted flare fittings, which is what stock GM fuel pumps, quadrajet inlets and brake lines use. The stock fuel inlet fittings on dual feed holleys are also inverted flare. When buying fittings make sure of what you have. NPT and inverted flare will not work together. A 3/8" steel brake line like GM used to make fuel lines has a 5/8"x18 fitting.

If I'm not mistaken don't you have a single feed 600 Holley? If so, here's what you'll need.
Banjo fitting
npt to an adapter
fittings
line
and don't forget a filter

This stuff gets pricey, but if done right, it can look really nice and professional.

[LuckyHenriksen]

Originally Posted by 68Stepbed

You also need to watch out for inverted flare fittings, which is what stock GM fuel pumps, quadrajet inlets and brake lines use. The stock fuel inlet fittings on dual feed holleys are also inverted flare. When buying fittings make sure of what you have. NPT and inverted flare will not work together. A 3/8" steel brake line like GM used to make fuel lines has a 5/8"x18 fitting.

If I'm not mistaken don't you have a single feed 600 Holley? If so, here's what you'll need.
Banjo fitting
npt to an adapter
fittings
line
and don't forget a filter

This stuff gets pricey, but if done right, it can look really nice and professional.

Thanks for your response, it was nice of you to list that all for me, but I am planning the new fuel system for the new motor! The plan calls for under bed alum. fuel cell from FCG, Carb'd 6.0 pushin 550 HP backed by my TH400. I plan on running either a 750 or 850 Holley DP or Demon, whatever I can get the best deal on. But I do need help setting up the fuel system for that. I bought a Holley Billet electric pump and regulator, but where do I mount this stuff? Any ideas?

[8mpg]

Mount the pump near the back end of the trunk. Near the tank. Filter after that and regulator up by the motor. Are you going to run a return line or just dead end it into the regulator? If you run a return, it will be cheaper to run the regulator near the pump.

Use some aluminum 3/8" fuel line from Summit. Its like $20 and comes in a 20' roll. It will be plenty to do the truck. Braided line is nice but to darn expensive and usually overkill.

[LuckyHenriksen]

I like the looks of the aeroquip StartLite line, its the black woven type. I think it looks so much nicer when its black. I hear of guys going to hydraulic shops and buying the line. I am going to try to get some on one of our company accounts somewhere, so its cheap or free! Can I mount the fuel pump in the frame rails? And don't I put the filter before the pump?

[8mpg]

Originally Posted by LuckyHenriksen

I like the looks of the aeroquip StartLite line, its the black woven type. I think it looks so much nicer when its black. I hear of guys going to hydraulic shops and buying the line. I am going to try to get some on one of our company accounts somewhere, so its cheap or free! Can I mount the fuel pump in the frame rails? And don't I put the filter before the pump?

Yeah... it can be in the frame rail.

You want the filter after the pump. A high micron filter will starve the pump. Put it after and your regulator after the filter. The pump will pump more fuel than you know what to do with and wont have a problem pushing through the filter...then you regulate it down.

[myoldchevytruck]

Originally Posted by Shane

-6 AN = 3/8"

Take the AN size and put it over 16 and reduce the fraction to get the -AN TUBING SIZE ... NOT the thread size.

-AN and NPT have absolutely nothing to do with one another. NPT is the tapered thread end that threads into the fuel pump housing and the 6 -AN is the end that is going OUT and holds the 3/8" (-6 AN) tubing.

4/16 = 1/4"
6/16 = 3/8"
8/16 = 1/2"
10/16 = 5/8"

Here's a link that might help ya too ... AN Tube & Thread Size Chart

Shane, That AN Conversion Chart Has Helped Out Many Times Over. Thanks for the great reference.

[LuckyHenriksen]

Originally Posted by 8mpg

Yeah... it can be in the frame rail.

You want the filter after the pump. A high micron filter will starve the pump. Put it after and your regulator after the filter. The pump will pump more fuel than you know what to do with and wont have a problem pushing through the filter...then you regulate it down.

Ok, but I hear about people getting grit in the pump, which causes it to fail. Is there supposed to be any kind of pre-filter before the pump?

[8mpg]

Originally Posted by LuckyHenriksen

Ok, but I hear about people getting grit in the pump, which causes it to fail. Is there supposed to be any kind of pre-filter before the pump?

You can run a universal strainer type filter before the pump if you want. You can pick up a cheap on at Napa for $5. Or if you want to spend the money, you can get a nice cleanable one from summitracing like this: http://store.summitracing.com/partde...5&autoview=sku

That is the -6an..they have a -8an one as well for the same price.

[LuckyHenriksen]

So if I put it in front of the pump, I still need another one after? Does it go before or after the regulator?

[8mpg]

Originally Posted by LuckyHenriksen

So if I put it in front of the pump, I still need another one after? Does it go before or after the regulator?

If you are going carb...probably not. If you go EFI, Id recommend a 10 micron filter after the pump. Injectors can get clogged way easier than a carb jet

[Ackattack]

for some efi pumps you may not want to put a filter before the pump because the fuel is used to cool the pump. if the filter gets clogged, and the pump is starved of fuel, it may burn up the pump. Just something to think about.