Lotus Elan

Modern nylon 1/4" fuel line . . . with an olive?

PostPost by: Sea Ranch » Sun Jan 01, 2017 2:39 am

Greetings and Happy New Year!

Re-doing my fuel line during the restoration. Would like to continue with 1/4" OD fuel line, as per factory, so I can re-use the brass banjo fitting at the tank and the standard fuel pump fitting: 3/8-24 male pipe nut with olive on the fuel line. Don't want to convert to AN lines and fittings, and don't see the benefit to using Cunifer line (much as I love the stuff and am gearing up to install it as brake lines) because I then have to use probably compression fittings to switch to some sort of flexible line from chassis to fuel pump for flexibility/vibration.

So, question: can I put a brass olive on this stuff: 1/4" OD modern nylon fuel line . . .

http://www.jegs.com/i/JEGS-Performance- ... 5/10002/-1

jeggs-quarter-inch-od-nylon-fuel-line.jpg and
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PostPost by: StressCraxx » Sun Jan 01, 2017 5:34 am

Yes, a compression nut with an olive was the original solution.
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PostPost by: Sea Ranch » Sun Jan 01, 2017 6:56 am

Right. Thanks, Dan. I see that (the original solution) on my car. I guess I'm asking if this stuff we now call nylon fuel injection line is "like" the original, and if it can sustain the compression of an olive and nut, and seal effectively. Like the original stuff.

I see that Ray at RD Enterprizes suggests that the original black plastic fuel line was indeed nylon, too. Do we have accounts of it failing due to ethanol use? I assume it fails simply through decades of use, exposure to the air and fuel. But was the original stuff vulnerable to ethanol (alcohol) in the fuel, or just simply old age?

In any case, it is my preference to use this "black plastic", if it's labeled nylon, and the original style connections. Anyone see a long-term problem with this?

Thanks! :mrgreen:

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PostPost by: vincereynard » Sun Jan 01, 2017 11:54 am

From a domestic plumbing POV it is generally thought that a copper olive is better for plastic pipe as being so much softer than brass it takes less torque to compress.
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PostPost by: Craven » Sun Jan 01, 2017 12:21 pm

Hi,
If you have managed to source the correct wall thickness tube then the original fitting method is fine, remembers it is on the suction side of the pump and only needs to be nipped up.
If you have a thin wall tube then you should use as with any deformable tube use an insert.
Ron.
Ps. I have an off cut of modern nylon tube immerse in today?s petrol for some 3 months now with no apparent ill effects.

20130106compressioncloseup.jpg
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PostPost by: Elan45 » Sun Jan 01, 2017 3:31 pm

My Super Safety has had a copper fuel line since 1985. My biggest fear with any car I've restored is FIRE. And nylon or any plastic fuel line is suspect to me.

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PostPost by: tedtaylor » Sun Jan 01, 2017 5:04 pm

the plastic fuel line is tucked up into the central frame tunnel and comes no where near the hot exhaust, thus no fire hazard in that respect.
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PostPost by: StressCraxx » Sun Jan 01, 2017 5:06 pm

Sea Ranch wrote:Right. Thanks, Dan. I see that (the original solution) on my car. I guess I'm asking if this stuff we now call nylon fuel injection line is "like" the original, and if it can sustain the compression of an olive and nut, and seal effectively. Like the original stuff.

I see that Ray at RD Enterprizes suggests that the original black plastic fuel line was indeed nylon, too. Do we have accounts of it failing due to ethanol use? I assume it fails simply through decades of use, exposure to the air and fuel. But was the original stuff vulnerable to ethanol (alcohol) in the fuel, or just simply old age?

In any case, it is my preference to use this "black plastic", if it's labeled nylon, and the original style connections. Anyone see a long-term problem with this?

Thanks! :mrgreen:

Randy


Hello Randy,

I have the original nylon fuel line in my 67 Elan. I inspect it whenever I have the carbs off. There is no sign of deterioration at all. We have used oxygenated fuels here in Kalifornia, the State of Desperation since the late 1980s, including MTBE and Ethanol. No effect at all.

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Dan
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PostPost by: Sea Ranch » Sun Jan 01, 2017 7:40 pm

Okay, here goes . . .

Vince, nice idea about the copper olive. Where do you get such a thing?

Craven, that insert looks very trick. Where do you get such a thing? And thanks for sharing about your little chemistry experiment. Good to know. :)

Roger, good to know that pure copper is handling the ethanol and other additives so well. We hear reports about possible problems with pure copper fuel lines.

Ted, agreed about the safe location, as long as the attachments are fool proof/fatigue proof. Of course, it's a double-edged sword, because this "safe" location for the fuel line, and the good attachments, means it's almost always a "body-off experience" to replace the fuel line!

And Dan: thanks so much for sharing your experience. When I took off the body and looked at the black fuel line, it seemed so . . . so skinny. But honestly, mine was just fine, too. Unfortunately, I threw it out as I figured at the very least I needed some new stuff, even if it was the same, so it could last another 46 years. Only kept a stub at each end to remind me what it was. :)

Anyway, I believe I will source some and do it again. :) If I could find some of the those inserts, and copper olives, even better!!

Regards, best of the new year to you all . . .

Randy
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PostPost by: RichC » Sun Jan 01, 2017 7:47 pm

I have some olives which i obtained to go on my original red fuel line . They are shouldered to prevent overcompression . I'll try and dig out some pictures
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PostPost by: Sea Ranch » Sun Jan 01, 2017 7:51 pm

Ahhhh . . . I might know what you mean. The olive on one end it not exactly hemispherical in cross section. I thought it had deformed from serious torque/compression. Perhaps it was made that way??

Thanks, Rich. Will wait for your pix . . . :mrgreen:
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PostPost by: TroonSprint » Sun Jan 01, 2017 8:03 pm

I used PTFE (teflon) pipe. It is flexible but fairly rigid, takes an olive without collapsing, and after a lifetime in laboratories I know that it is one of the most solvent tolerant plastics ever made.
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PostPost by: Sea Ranch » Sun Jan 01, 2017 8:48 pm

Okay; sounds like a good tip, Troon.

Can you tell us what name brand or specific product we're talking about and/or perhaps a retailer?

And are we talking about 1/4" OD piping?

Thanks, :mrgreen:

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PostPost by: Sea Ranch » Sun Jan 01, 2017 9:12 pm

Here's an example in North America . . . no mention of fuel, but it is PTFE . . . 1/8" ID is pretty small. The factory stuff is a little bigger ID, thinner wall thickness. 1/2" bend radius is very good flexibility, though.

http://www.usplastic.com/catalog/item.aspx?sku=58053

Interestingly, the output port of the original AC fuel pump is the same connection as the input. Yet the stainless braided loom for pump to carbs has a copper tube and olive for the pump end that is 3/8" diameter. Presumably this means you could use 3/8" OD fuel line INTO the pump as well (with an appropriate brake line nut for 3/8" tubing) and that would be fine, too. Except you would have to find a banjo fitting to accept 3/8" line for the tank-end fitting.
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PostPost by: TroonSprint » Sun Jan 01, 2017 10:45 pm

I bought the pipe from an ebay seller. I don't recall which one I'm afraid. If you search PTFE tube on ebay you will find many sizes available. I think I bought 8mm OD which is about 6mm ID, but the old memory is a bit hazy on the details! I used barbed connectors in the engine bay and found that by warming the tube in very hot water I could get it over the barb, When cool it gripped tightly and I used a small pipe clip to secure it.

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