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Having done some major changes to my car I am now working on routing the fuel lines. I have some summit racing twist-lok -8an hose that I was using. Due to the new placement of the tank the previously cut lines are too short. They terminate in the tunnel of the car. I have the extra length to make them fit but I'm hesitant to add another splice. If I do splice I'll use a one piece barb/push lock union.

Now looking at unions I have found a brass unit for industrial apps for about $2.50. The "racing" aluminum jobbers are $14 a piece. Will the brass work?

Next I purchased these lines in 2012 and they were rated for fuel. Apperantly a few months later due to changes in fuel types a warning was put that they aren't for fuel although they are still nhra approved. I only plan on running pump gas through them. Should I get new fuel hose?

i like the idea of the push-loc hose because I can run it front to back with a minimal amount of connections. I could do hardlines but that adds more connections. Plus I can't seem to find a source for steel 1/2 coil tube. Everything is aluminum. Is aluminum hardline safe to use if it is well supported?

In summary my options are splice/Mend what I have. Get new push-lok in the proper length or replace center section with hardlines and have push-lok on the front and back.


Evo

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My vq30 middy build http://www.locostusa.com/forums/viewtopic.php?f=36&t=4082

Brass is fully compatible with all motor fuels. A splice won't be any problem.

*However...*

I've had to replace the rubber lines on several cars and a few motorcycles in the last decade or so due to the rubber hoses turning to goo on the inside. Those were Gates fuel lines, not cheap stuff.

The culprit seems to be ethyl tertiary butyl ether and methyl teriary butyl ether (ETBE and MTBE), which are added as "oxgenates." Basically to reduce emissions in old-school carbureted cars in poor tune, which are statistically nearly nonexistent nowadays. But we still get high percentages of butyl ethers because, mainly due to how taxes work, it's cheaper than gasoline and thus more profitable per gallon.

I've had enough problems, including having to have one vehicle recovered from out of state (the fuel pump was plugged with gummy rubber from the return line) that I'm leery of any rubber in the fuel system.

Obviously not all rubber lines or liners are susceptible to the problem, but I'd either go with hard line or make sure there was access to all the fuel line clamps in case I had to replace it sometime in the future.

There is no question steel hardline is the safest bet. Aluminum is far more crack prone (although I have never seen it myself), and it must be supported correctly. The brass JIC fittings will work fine. They contain thousands of psi of hydraulic fluid with no seepage, so 50psi of fuel is nothing. For 1/2" line try talking to a hydraulic shop. It's too big for automotive applications. I know you can get stainless 1/2".

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I use a lot of Swagelok stainless tubing and fittings at work, and am a big fan of them. Instead of trying to bend up a stainless line to go through my tunnel though, I ran some 3/8" OD plastic tubing called Synflex and used stainless tube and a bulkhead fitting where it comes out of the tunnel. Synflex is used as air line on big trucks and is rated for something like 250 or 300 psi, plus is compatible with pretty much any fuels or solvent. I've posted a link to the manufacturer site here before, but I can't remember where. Truck shops also sell various brass compression fittings that is used for Synflex, which I would use if I didn't have lots of slightly used Swagelok stuff from work.
Kristian

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V6 in a book frame build. Now registered.
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I'm thinging I may just splice what I have and use it for testing purposes and when it comes time for final assembly switch to ptfe teflon hose which will never need changing.

The cost of steel 3/8 lines really started to add up with all the fittings and I would still need some rubber lines. Plus doing the whole car with steel lines would be a big task to try to have the minimal amount of unions. With ptfe my only additional unions are reducing the line down to 5/16 from -8an.

Evo

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My vq30 middy build http://www.locostusa.com/forums/viewtopic.php?f=36&t=4082

It's hard to avoid *some* rubber in the system. At the OEM level, there's usually a short piece of rubber hose between the fuel pump and the metal line... and you have to have something flexible to go from the chassis to the engine. As long as the manufacturer certifies the hose for use with alcohol you should be okay.

If you use AN fittings, the aluminum ones are subject to corrosion from alcohol or alcohol-bearing fuels. Most people use aluminum and have no trouble, but stainless steel fittings are also available. There are also AN-compatible 37-degree "JIC" fittings, usually in brass, found mostly on farm equipment. But they typically have John Deere or Caterpillar prices, which make "aircraft" stuff look cheap... the JIC fittings are the cat's meow if you want to braze a bleeder fitting onto a brass radiator tank, though.

I have had enough bad experiences with plastic lines that I'm willing to pay a premium to avoid them, but you might email the makers of that Synflex line Kristian mentioned and see what they say about fuel compatibility.

I ran 5/16 steel brake line for both feed and return. I wasn't looking for big HP so 5/16 was plenty. I used rubber fuel hose (E10 & fuel injection rated) for the flexible areas. I bubble flared the ends of the brake lines to prevent the hose from accidentally slipping off. I know it is not for everyone but it is economical, reliable and inexpensive.

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Chuck.

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Well I was going to try to use what I have for testing but I realized that this hose is shot. It is so hard that I can't get new fittings on it. I have a bit of aeroquip hose that was used and it is still playable, just like the unused twists-tite hose I have. Seeing as the old "2012" stuff is rock hard I'll have to replaced the lines anyway. Guess I should work a little faster before more things turn to dust.


Evo

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My vq30 middy build http://www.locostusa.com/forums/viewtopic.php?f=36&t=4082

Do you remember what brand/type the hose was? It sounds like something to avoid in the future...

5/16" should be plenty. Despite the trend toward giant fuel lines, a friend's big block '65 Impala is still running the original 5/16" fuel lines, and he pulls both front wheels off the ground at the drag strip... we put a fuel pressure gauge on it a few years ago and it's still 6 PSI when he goes through the traps.

It was summit brand twist-tite. One issue is my fuel tank has -08an out of it. I already have it set up for -8 all the way to the last bit where a few adapters take it down to 5/16 rubber.


I found there is a hose from Jegs that uses Viton and can use push fittings. Viton is PCTFE while teflon is ptfe. Ptfe needs ptfe fittings. Both hoses are $170 for 20 feet but everything I have read is that ptfe will never deteriorate as it has no rubber in it. Down side is it needs ptfe fittings which aren't cheap.

Evo

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My vq30 middy build http://www.locostusa.com/forums/viewtopic.php?f=36&t=4082

PTFE/Teflon exhibits what is called "cold flow." When loaded, it deforms like a much softer material, so it's hard to get a good grip on it over time.

Hm. Some AN hose is Teflon with a braided cover; I have some out in the shop. I've never seen any special fittings for that, or heard any stories of fittings coming loose.

[sigh] I feel another looong evening with the search engines coming on...