Another fuel line question

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I am getting ready to mock up fuel lines on my car and I need some guidance. I have a modified fuel tank with 1/4" NPT fittings on top in a slightly recessed area near the sending unit. The pump is in the tank.
I need to come off the top of the tank and forward, then turn to the right after the front of the tank, kind of like the way GM did it with the stock lines. After that I will be running into a filter and forward with steel or plastic lines.
I think that I need to make enough tight turns at the tank that I'd prefer to use steel there as well. I'm a little worried about braided lines chafing something or getting chafed and I don't want to worry about fuel smell seeping through the lines.

Whadd'ya think?

[Kokamo]

I would suppose the steel line would be superior to the braided line....for the part you are working on (out of the tank and to the filter). The braided line is much larger in diameter....prolly twice as large, so yes, the chaffing/rubbing and possible blowout would be a concern for me.

If at all possible, use some cut fuel lines over the steel line to prevent any rubbing or rattling.

Hope this is what you were looking for,

~Joe

[CarlC]

If you have an NPT facing up you will likely need a short 90* screw-in fitting to clear the trunk floor.

From a service perspective you want to be able to disconnect the lines in such a way that they come down with the tank. In other words, the lines need to disconnect from the frame lines near the tank so that the tank can be removed/installed easily.

Teflon hose, which will last the life of the car, has a much smaller OD than standard AN.

[Kokamo]

Carl, your right....didn't think about the 90 in there.

If it's what I have dabbled in my mind, you would need a 90 since either steel line or braided line would be at too much of a bend to make it work properly.

Do you have any pictures of what your working on?

~Joe

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Yes, I will need to use some kind of 90.
I was thinking about running the lines almost the same way as the stock lines do, steel from the tank to the frame rail, some kind of flexible connection, then steel (or plastic) up to the front.

[CarlC]

If it's what I have dabbled in my mind, you would need a 90 since either steel line or braided line would be at too much of a bend to make it work properly.

Do you have any pictures of what your working on?

~Joe

You got it. The stack height of an NPT to -6 straight adapter + the height of a 90* -6 hose fitting would likely be close to 2". There may not be that kind of overhead clearance available. There's more info on my car in my website using the link below, or there's a thread in Project Updates https://www.pro-touring.com/forum/sh...ad.php?t=42290

GetMore, (BTW, please include your name in your posting signature.)

A stock hardline will work fine, as will a similar stock routing. A stock hardline just needs to be flaired to fit whatever connections you will use. It makes installation easy since someone has already done the bends. If it is stainless there are no worries, but if it is mild steel you may want to consider using a filter on the end of the hardline. Injectors and metal corrosion particles do not get along well.

The OE brazed tube through the top of the sending unit/pump access is very compact and reliable. Hopefully your tank was recessed enough to allow a simple 90* to be used.

It is good to have a flexible connection near the frame rail.

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I have pictures somewhere. I've just got to find them.

The top of the tank does have a recess, IIRC it is just over 1". I had notes for myself somewhere that had the height of the stock lines over the top of the tank and the recess in the new tank. IIRC (again) it was just over 2" of clearance.
I know that if I use a tight 90 it will fit under the top profile of the tank, but I'm not sure what kind of flow restriction it will cause. Considering that the bungs are only 1/4" NPT I realize that I already have some limit on flow. (Really, I don't know why they used something so small. I do know that they said that since it is such a short distance it won't really effect the flow. I should probably see what the ID is of the line from the pump, maybe that is the smallest part.)

[CarlC]

What pump does the tank have, and what kind of power is the engine going to make? I'm running a 255lph Walbro through -6 lines, which means there are restrictions down to near 5/16". With 530+ HP at the crank there are zero fuel problems.

[s4dustin]

What about that Mr. Gasket press on fuel line?

Pulled the old line out today...

I was told that if I go Aluminum I would be fine...now I am wondering about steel braded or the mr. gasket press on.....

any suggestions?

I bought the tools to bend the tubing today and for flaring....

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I kind of said the heck with it, and just bought some teflon hose and fittings. I'm going to at least run from the top of the tank to the front of the tank with teflon, may install some 90° fittings to make the turn, may adapt to steel, I haven't decided yet. I'm going to see how much room I have, how tight a bend the line can make, and how I'm going to hold it in place so I can decide.
Now I just have to verify what size line to run.

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What pump does the tank have, and what kind of power is the engine going to make? I'm running a 255lph Walbro through -6 lines, which means there are restrictions down to near 5/16". With 530+ HP at the crank there are zero fuel problems.

Thanks for that info. It looks like I'll work with the -6 teflon hose and some 3/8" line. I doubt I'll be making more power than you are, so that should be fine for me.
I played around with some fittings today, and it looks like the ID of the 1/4" to -6 fitting is about 5/16" on both halves, but the ID of the -6 elbow is about 1/4" where the hose goes over it, FWIW.

I measured the tank and the underside of the floorpan this weekend, and I do have about 2" of clearance. I installed an adapter nipple and a small 90° fitting, and they sit just over 2" high, so things are going to be extremely tight like that. (I still have to install an isolator strip between the tank and the floor, so I may get the clearance I need.)
My other choice is to use a 90° adapter fitting, whick will keep everything really tight, but I'm concerned about the lack of sweep in the fitting causing restriction. Does anyone know of a 1/4" NPT to -6 90° fitting that has some sweep to it?

I've loaded some pictures: The first is the top of the tank, showing the cutout. The second is the underside of the trunk floor over the sending unit of the tank, and the third is a front view of the tank with the nipple and 90 installed.

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What I'm currently considering is running the lines straight forward from the tank to the small reinforcement that runs between the frame rails. This is right behind the bottom of the rear seats, I think. This location is where the stock vent line crosses from one frame rail to the other.
The only issue I have with this location is that it is right over the rear diff and crosses over the muffler. Not ideal, but maybe it'll work.
I figure I'll sleeve the lines with a heat protective liner, so that should handle the heat issue and add a little protection.
I'll clamp the lines to the floor and/or the crossmember to keep them in place and make the corner.

Let me know what you think. I'll try to get it in the air and maybe see how the lines sit and get some more pics.