Primoz

Hi,

I will change the fuel lines on my 71 SB with new ones. Probably braided AN style since I can get them in my country without the need of importing from USA.
Question is what sizes are the lines and does the size matter?
I think they are 3/8" originally or am I wrong?

I liked this setup from one of the guys on this forum:

doorgunner

I think the supply line is 3/8". The return line (if your car has one) may be smaller. I'm guessing you could make both lines 3/8" to make it simpler to buy, but you have to make sure that the return line will not leak (because it is too large) where it connects to the gas tank return and the fuel pump.

Wait for expert members to advise you.

v2racing

That's my car. I used -8 AN on the feed and -6 AN on the return. That corresponds to 1/2" feed and 3/8" return. I was setting up a system that will support up to 750 HP.

For most applications, 3/8" or -6 feed will be fine. A return of 1/4" or -4 will work for the return.

Mike

HeadsU.P.

I like the look of braided, but is it DOT legal along the frame?
No matter how good it looks, no matter how easy it is to install, no matter how expensive it is, I would not feel safe using braided line the entire length of the frame. Braided is fine where a visual inspection is easy to see such as pump to carb, in short lengths and nothing can crush, sever or bind on the fuel line. Braided is just dress-up rubber hose.
Where do sanctioning bodies like NHRA, Rally and circle track stand on this?

ignatz

That's all you need to know about these. Personally I wouldn't do it and it is mostly hidden anyway so who cares how it looks?

The standard lines are 3/8" source and 5/16" return. You haven't mentioned the condition of your car. Is the body off? Do you have the old lines to use as a template?

While I haven't done it myself with the body on, others apparently have so you should dig a little deeper on this subject.

As to the material, SS is a bitch to shape and it ships folded in half. If you ship from the US, just get the steel lines. My understanding is that the tubing used in Europe is pretty easy to shape and different from our steel tubing here. It might be easier than you think to make your own lines.

metal tech

I would not use stainless braided rubber line for fuel use on a daily driver. The additives in pump gas is known to soften and damage the rubber inside braided line and with the stainless cover you won't see any bulging. If you want to run "flex" line use the PTFE/Teflon line, the additives won't harm it. You could use stainless hard line for all but connections at the gas tank & carb. I'd use no thicker than .028 wall, it's not the bending that's an issue, it's making a flare that becomes more difficult.

C3 Stroker

NHRA legal from tank to engine along the frame, but not near or around the trans/firewall unless running through a tube. Typically done from fuel cell to fuel pump. I have the 1/2" black braided line the entire length, and from pump to carb.

ajrothm

As do I.

-10 braided hose from the tank to the carb.
-8 return from the regulator to the tank.

Mine is ran along the frame very similar to V2 Racing’s....

It’s NHRA legal, and plenty safe no where can it get hit or pinched. If I got T boned hard enough to rupture the fuel line inside the frame, the fuel line would be the least of my worries.

PainfullySlow

Just so we are clear, braided hose is NOT just dressed up rubber line. The core is the same but it has vastly superior crush, cut, and expansion resistance.

That said, I would still prefer a steel line along the frame as long as it was stainless steel.

v2racing

Braided line like I am using is rated up to 350 PSI pressure, which I have exceeded in Top Fuel use without issue. I have seen as much as 500 PSI put in this line. I don't think 15 PSI up to the regulator like I am running will ever be an issue.

As far as being attacked by fuel additives like ethanol, that is also a non issue. The line is used for nitromethane, methanol and race gas also without issue. These fuels make pump gasohol look like water in their ability to attack materials.

I personally had an underhood fire in my 64 Impala SS that melted aluminum and zinc (carb). The braided fuel line was still intact and still held pressure when I tested it.

As for it getting cut in an accident, anyone who has ever used the sharp chisel method of cutting braided line knows it takes a lot to cut it. Just getting bent sharply is not going to penetrate it.

Bottom line. The stuff is pretty damn tuff!

The thing that can destroy braided line is abrasion on hard sharp objects. You have to take care in routing it and secure it so it stays away from harm. Other than that, I would not worry about it.

Mike

Rescue Rogers

They make braided line that is ptfe lined so its not an issue with the alcohol fuels. Besides ethanol is a US thing, I dont think any other countries use it.

Primoz

My car is not body off but I will lift the body to change the body mounts. Not full frame off but just enough to change the body mounts.

ignatz

The stuff I was trying to remember is called "Kunifer" , don't know if it is available where you are