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What is the best material for gas fuel line?

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Old 06-07-2005, 12:00 PM
  #1
Kmot
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Default What is the best material for gas fuel line?

I need to replace the line on my Fire Hammer with some tubing that is more resistant to heat affects. Can nitro model silicone tubing be used with gasoline? If not, what is the best, high temp resistant, gasoline tubing to use?
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Old 06-07-2005, 03:00 PM
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Default RE: What is the best material for gas fuel line?

Check Tower Hobbies out. I don't believe you can use the silicone tubing nitros use, I think you need to get some Tygon tubing. You can probably take a piece of your original line to an auto parts store, they can probably set you up too.
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Old 06-07-2005, 03:52 PM
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Default RE: What is the best material for gas fuel line?

Or any lawn and garden store will stock it for dirt cheap. Same fuel line used on weedwackers and small lawnmowers, hedge clipprs, chain saws, etc.

Don't pay high hobby prices when you can get the same if not better stuff at a local store for 1/10th the price.
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Old 06-07-2005, 07:41 PM
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Default RE: What is the best material for gas fuel line?

Tygon? Okay, will check it out, thanks.

Not sure if automotive would be any different than what is on there now. Cuz I have a heat problem due to the line laying next to the tuned pipe.
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Old 06-08-2005, 04:40 AM
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Default RE: What is the best material for gas fuel line?

Buy some heat proof sheathing and fit it over the tubing where it's close to hottest parts (usually the carb tubing runs on or near the engine head)
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Old 06-08-2005, 04:50 AM
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Default RE: What is the best material for gas fuel line?

This is the tubing I use with success and no damage from heat. I would recommend repositioning the fuel line so that it does not come into contact with a heat source.

http://www2.towerhobbies.com/cgi-bin...?&I=LXD734&P=M
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Old 06-08-2005, 05:31 AM
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Default RE: What is the best material for gas fuel line?

Got some of braided fuel covers but not enough for all three tubes (the one that goes around the fan, vent tube that's near the spark, other one near the spark) not actually touching engine but probably, haven't had problems with damaged one near the fan but I'll do it anyway to protect it - most heat damage are the lines around the top of the engine.
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Old 06-08-2005, 12:23 PM
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Default RE: What is the best material for gas fuel line?

I did a little research. It seems Tygon is a good choice, as well as "neoprene" synthetic rubber.
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Old 06-08-2005, 03:31 PM
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Default RE: What is the best material for gas fuel line?

If you're looking for the ultimate solution:

Go to an automotive race shop (like Summit-Racing for example) and get some AN-3 Teflon hose. It has an inner diameter of 1/8", outer dia. is 1/4" and it's stainless steel braided. Yes, it is expensive ( about 16 bucks for a 3' piece), but this thing is tough. You can even use it as a brake line for real cars. Operating pressure is 3000 psi, permanent temperature range up to about 230 °C....
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Old 06-08-2005, 06:11 PM
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Default RE: What is the best material for gas fuel line?

Fitted the braided sheathing, just need two more. Used click ties to stop the edges fraying.
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Old 06-08-2005, 07:41 PM
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Default RE: What is the best material for gas fuel line?

Mad Wax: you can also use heat shrink tubing to keep the ends from getting messy. Here is my boat with sheathing I installed over the cooling line:

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Old 06-08-2005, 07:55 PM
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Default RE: What is the best material for gas fuel line?

Hi chevyman_de: I am quite familiar with AN hose. Have used it for my entire carreer. The problem with using it in this application would be that it can't make a tight enough radius since I can't use hose fittings. Also, you must use hose fittings, although in a non pressurized application you could get away with hose clamps. Fitting it over the barbs would not seal and I gaurantee you a leak if not clamped tightly, even with a gravity feed line.

The braided shielding is not for temperature protection, but merely for abrasion resistance. Although the Teflon liner is rated to several hundred degrees Farenheit, I have seen it crumble from the heat of compression from on-board air compressors in buses.

I have some -3 hose and lots of Weatherhead fittings in my possesion as I type. Unfortunately it is not applicable to this little engine.

Along the lines of this subject, I found some rubber fuel tubing made from "Viton" which has a temp rating up to 400*F.
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Old 06-08-2005, 08:09 PM
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Default RE: What is the best material for gas fuel line?

You are making a mountain out of something that is simple here. Alls you need to do is get fuel line that says diesel or Gas on it, not standard Nitro R/C can be gotten at any R/C store, or as the one guy said Tower Hobby has it.
Here is how I routed mine and all works great.



Makes it clean on the other side where a pipe needs to go
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Old 06-08-2005, 10:03 PM
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Default RE: What is the best material for gas fuel line?

You don't have the XTM tuned pipe. That's where the trouble starts........
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Old 06-08-2005, 10:19 PM
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Default RE: What is the best material for gas fuel line?

Here, I just took a picture. Maybe this will help explain my situation.

The fuel line is bent 90* and fully against the tuned pipe. The barbed fitting on the carb cannot be rotated, that I can tell.
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Old 06-08-2005, 10:23 PM
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Default RE: What is the best material for gas fuel line?

Jeff, your barbed carb fitting is pointing the opposite direction of mine. Did you rotate it? How? That is exactly the solution to my problem!
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Old 06-08-2005, 10:52 PM
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Default RE: What is the best material for gas fuel line?

Yes, that is why I posted those pictures so you could see that by moving the lines to the right side all will be clear. Just take the air cleaner off and spin it (BE EASY) not to break it, they are just screwed in. I put the clear fuel line on it so I can make sure the carb is filled with fuel and you can see that it is going to the return also.


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ORIGINAL: Kmot

Jeff, your barbed carb fitting is pointing the opposite direction of mine. Did you rotate it? How? That is exactly the solution to my problem!
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Old 06-08-2005, 11:56 PM
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Default RE: What is the best material for gas fuel line?

Alright, I'm going to give it a twist. Thanks!
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Old 06-08-2005, 11:59 PM
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Default RE: What is the best material for gas fuel line?

Thanks for the input on those lines. I was aware of the points you mentioned. Well, most of them as the problem of the minimum radius slipped my mind.
Tight clamping is a necessity with teflon hoses, but I think it should work with this no-pressure application, if done properly.
Of course the braiding is for abrasion protection, but I found that it distributes heat from a punctual contact over a wider area. Nevertheless heating the fuel is always a bad idea, so re-routing the fuel line would be best.
Btw, I searched for AN-2 fittings, but was unaible to find some except for a single straight version. Do you know a 90° fitting - or even better - a banjo bolt type of this size?
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Old 06-09-2005, 12:37 PM
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Default RE: What is the best material for gas fuel line?

chevyman_de: The only banjo bolts I use are the ones on my personal vehicle brake system. In the equipment I work on, our brakes are air powered and we don't use banjo bolts for anything. The smallest AN lines I have worked with are -3, used for the oil cooling line on alternators, and they have a straight female on one end and a 90* female on the other and screw onto brass Weatherheads.

Try Goodridge, maybe they have what you are looking for:

http://www.goodridge.net/index.html
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Old 06-09-2005, 03:02 PM
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Default RE: What is the best material for gas fuel line?

The braid on teflon is not for heat or abrasion resistance. Its for pressure... the teflon tube wall is thin (.030 or .040) depending on MFG. The stainless braid is what gives it the pressure rating of 2500-3000 psi working depending on MFG. I have tried it on RC large scale and it will work, but is not so good for bouncing around with. It will come undone or even worse let in air! There is a 3/16 ID hose thats available with a stainless cover and that is much better, but the OD is much larger then the teflon.
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Old 06-09-2005, 06:34 PM
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Default RE: What is the best material for gas fuel line?

Quote:
The braid on teflon is not for heat or abrasion resistance. Its for pressure...
Good point. But it is also used extensively in low pressure situations where abrasion resistance is needed. That is how we use it. For the really high pressure stuff (CNG) we use stainless steel tube.

Back on subject: Jeff, thanks alot for the tip on rotating the carb fitting. I thought for sure it would snap if I did but it didn't! Turns out also that it was merely the return line. Doh!

I have converted to Tygon and while doing so found the return line had melted through at the 180* bend of the tuned pipe. And the fuel feed line at the underside of the carb was split on the barbed fitting. That is where my engine was going lean! Really cheap quality rubber line on these buggies, everyone should replace that stuff.

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Old 06-10-2005, 05:17 AM
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Default RE: What is the best material for gas fuel line?

Thank you for the link. I'll check their site.
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