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Need help. Best fuel line for clunk

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Need help. Best fuel line for clunk

Old 03-08-2004, 08:22 PM
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JLMG1971
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Default Need help. Best fuel line for clunk

Hi
I am having problems getting the clunk to get to all for corners of the fuel tank, at least past half tank when inverted. The problem is the fuel line not being flexible enough, I don't know what brand do I have but it is thick walled. I know there is a very thin walled and flexible fuel tubing but I don't know which make is it. Do you guys know who makes this thin wall very flexible 1/2A fuel tubing?
Thanks

Jorge
Canada
Old 03-08-2004, 09:08 PM
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jboy381-RCU
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Default RE: Need help. Best fuel line for clunk

i'm looking for some myself...if you run across any let me know...i'll do the same...you might want to try smallparts.com...they have some thin walled silcon tube,but i don't know if it's fuel proof...

john


here's a link

http://www.smallparts.com/products/d...ions/2100+.cfm
Old 03-08-2004, 10:05 PM
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William Robison
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Default RE: Need help. Best fuel line for clunk

Jorge:

Get with Sullivan Products, in Baltimore USA. They supply complete fuel tanks with good flex clunk line, and tank parts as well so you should be able to get it from them.

Bill.
Old 03-08-2004, 11:15 PM
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Dsegal
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Default RE: Need help. Best fuel line for clunk

With 1oz. and 2oz. Sullivan tanks the fuel line inside the tank is so short and stiff that the clunk will not move much. A real bummer. I guess that is why people go to balloon tanks.
Old 03-08-2004, 11:59 PM
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DesignMan
 
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Default RE: Need help. Best fuel line for clunk

Smallparts.com lists all kinds of exotic material tubing in a variety of sizes. Not cheap, but you only need a smidgen.... (any Tom Lehrer fans out there?)
Old 03-09-2004, 12:21 AM
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William Robison
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Default RE: Need help. Best fuel line for clunk

Larry:

Do you know which would be the correct tubing for a small tank? I've had the same problem Dave Segal mentions with the little ones.

"I hold your hand in mine, dear,
I touch it to my lips.
I take a healthy bite from,
Your dainty fingertips."

"There's ten stuffed heads in my trophy room right now,
Two game wardens,
Seven hunters,
And a purebred Guernsey cow."

Who's Tom Lehrer?

Haw.

Did you know he was a math instructor at Harvard? They fired him for writing "The Harvard Fight Song."

Bill.

PS: I don't think "Poisoning Pigeons in the Park" (you only need a smidgen) was really one of his good ones. wr.
Old 03-09-2004, 01:55 AM
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Motta
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Default RE: Need help. Best fuel line for clunk

Try with the fuel line that is included in some ARF´s
Is very flexible and works fine.
Old 03-09-2004, 05:15 PM
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mclintock
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Default RE: Need help. Best fuel line for clunk

Looking at the stuff in the tank of my rc bee, I posted on another thread that the clunk line looked to me alot like the rubber insulation on test lead wire. Looking again, I think another source of possible fuel line substitute would be the insulation from headphone wire, like the cheap ear buds or foam earphones supplied with a portable cd player for example. Most everyone has a drawer or box of those headphones and/or the ones that came with a long abandoned cell phone. Some of the headphone wire outer insulation I found is very thin and flexible, like thin rubber almost.
Who knows how it would stand up to fuel tho..
Old 03-09-2004, 06:14 PM
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Default RE: Need help. Best fuel line for clunk

It is probably P.V.C (or similar) based insulation- i was dissapointed to find the silicon looking tube they sell for fish tanks is not actually silicon and hardens with contact to methanol/oil. P.V.C will also harden up quickly.
The leads on your multimeter may be silicon- it is used as insulation in some e.p stuff
Check out this site- it is not the super thinnest in the world but I think it is what you are talking about- 1/8" Diameter.

http://www.the-printer.net/DookCat.html

In a thread a long time ago some guys mentioned tube made by robart.. I think?? It may have been AJC who new where it came from. I`d really like to get some really thing stuff too.

J.M
Old 03-09-2004, 07:28 PM
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JLMG1971
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Default RE: Need help. Best fuel line for clunk

I was looking at different manufacturers' websites and got this info:

Aerotrend I.D 5/64 O.D. 11/64
Dubro I.D. 1/16 O.D. N/A
General silicones I.D. 5/64 O.D. 11/64
Sig I.D. 1/16 O.D. N/A

Now, I could not get the O.D. of any 1/16 I.D. 1/2A fuel line. That could give a very good idea of which fuel line has its wall thinner, I'll mesure the fuel line that I have and see if I can figure out something.....
Old 03-09-2004, 08:03 PM
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captnhowdy
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Default RE: Need help. Best fuel line for clunk

Not the smallest I.D. but the most flexable.. I have used this for 3/4 inch round sheet brass clunk tanks for .010 stuff...

Aaron
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Old 03-09-2004, 08:13 PM
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William Robison
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Default RE: Need help. Best fuel line for clunk

Cap:

Thought Sullivan would have something. Refer my post #3.

Bill.
Old 03-09-2004, 08:17 PM
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JLMG1971
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Default RE: Need help. Best fuel line for clunk

Thanks guys, I'll try the SUllivan tubing
Old 03-09-2004, 11:23 PM
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Dsegal
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Default RE: Need help. Best fuel line for clunk

Will that Sullivan small tubing fit over the standard clunk?
Old 03-10-2004, 05:58 PM
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captnhowdy
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Default RE: Need help. Best fuel line for clunk

Dave,

Yes ! I thought of that last night and tryed it.

Aaron
Old 03-11-2004, 10:36 AM
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S. Christensen
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Default RE: Need help. Best fuel line for clunk

JLMG1971,
I've been flying small R/C models for many years and I have found that the best fuel tubing for "clunk" tank applications, especially with tanks in the 1 or 2 ounce sizes, is small diameter surgical tubing. This stuff flexes easily and works well with small "clunks". It has a 1/16" I.D. and a wall thickness of just 1/32". The SIG part number for the small 1' package is SIGSH284. You might ask you LHS to order you some or you could call SIG direct. Hope this helps.
Regards,
S. Christensen
Old 03-11-2004, 11:04 AM
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Default RE: Need help. Best fuel line for clunk

Hmmm, S. Christensen, Montezuma Iowa, SIG product advice....you must be Scott Christensen, THE MAN, SIG designer? Welcome aboard!

ps: Are there different types of surgical tubing? The latex stuff I used in 1/2A tanks worked great for a little while and then turned into a sticky mess. I lucked into a small quantity of silicone tubing with the same dimensions you noted which is very flexible but am about to run out of it.
Old 03-11-2004, 11:49 AM
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combatpigg
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Default RE: Need help. Best fuel line for clunk

I found this stuff at an archery supply. It has a 1/16" I.D., and is very flexible.
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Old 03-11-2004, 12:19 PM
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Default RE: Need help. Best fuel line for clunk

Looks like it needs Viagra [sm=bananahead.gif]
Old 03-11-2004, 05:41 PM
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Default RE: Need help. Best fuel line for clunk

ORIGINAL: combatpigg

I found this stuff at an archery supply. It has a 1/16" I.D., and is very flexible.

i need about 6 inches of that stuff...i went to the local med.supply store and turned up empty...will you send me some???

john
Old 03-12-2004, 08:39 AM
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S. Christensen
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Default RE: Need help. Best fuel line for clunk

DICKEYBIRD,
There well may be different "grades" of surgical tubing but if there are, I'm not aware of them. The stuff I've been using for years was purchased at hobby shops. In some cases it was SIG and in others, it was another company (can't remember the name). The bottom line is that it works and works well. Yes, it will eventually break down and will need replacing. However, I've found over the years that this is true with almost any kind of fuel line. I have a small .020 powered seaplane that has a custom made "clunk" tank in its pod. This model is in its 9th year and in that time, I replaced the "clunk" line once. Seems to me that this is an acceptable chore given the fact that the tank feeds fuel on demand and in any attitude.

Another really nice aspect of this small tubing is its use with Cox .010 and .020 TeeDee engines. It makes a great replacement tank/carb tubing for these small guys.

DESIGNMAN,
How are doing Larry? I haven't seen you in quite awhile. Will you be attending the upcoming Toledo Show? If so, stop by the SIG booth and say hi.
S. Christensen
Old 03-12-2004, 03:39 PM
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AndyW
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Default RE: Need help. Best fuel line for clunk

I share Dickeybird's concern over latex tubing so I did a search, some years ago for small sizes of silicone tubing. There are a lot of manufacturers out there that make a variety of very small sizes. At the time I ran an industrial supply store so it was easy to get three foot samples of sizes as small as appropriate to make clunk tanks even for .010 engines. Samples only because minimum quantities were 50 and 100 foot. []

Illustrated is my solution to the tank/clunk problem for small engines. Small poly bottles can be found at your local pharmacy. These contain hairspray, hand lotion and the like for the ladies. Once your wife or girlfriend are through with your " thoughtful little gift" you can salvage the bottle for your own use.

The trick is to not use the hardware for the stopper but instead, expand the neck of the bottle to a just snug fit for the stopper. The neck is cut off and the hole expanded just undersize with an Exacto. Final sizing is done with the Dremel sanding drum. By chance, this makes a hole with a perfect fit allowing the stopper to be stuffed in place without any difficulty but still snug enough to be leak proof even with muffler pressure. Apply the sanding drum by HAND, not with the power tool. Just shove it in, and twist and turn until you feel no resistance. Then, with 400 paper, smooth out the edges.

The next trick is to use the center hole (where the screw went) for your feed line fitting. I've made up a special little fitting with nipple ends to help keep the lines on. Using the center hole puts the clunk pick up in a more balanced location. One of the other holes in the stopper is used for your vent line and if you use a three line system the other hole can be your fill line. If you use a two line system, the third hole can be plugged.

The small red tubing and the clunk I got from Cox a great many years ago and were available for, I think, their Dragonfly engine. This had a tankmount complete with clunk.

Another solution I stumbled on occurred when I tried to find clunk tubing for small diesel fuel tanks. As it turned out, I found a source for some thin wall, flexible neoprene tubing. This stuff is just over 1/8" ID so Du-Bro fuel barbs need to be used on the brass tubing. The stock clunk, however, holds the tubing fine. This set up clunks properly in a two ounce tank and as neoprene is resistant to glow as well as diesel, would be the solution to clunk problems in small tanks for both types of fuel. Clunking is marginal in a one ounce tank but it's not bad and flight testing has shown no problems. As I'm no longer in industry, I had to order what I thought was 10 feet but as it turned out, there was a 50 foot minimum. A life time supply I guess, but I may not live that long. [&o] The excess, 40 ft, is for sale at a dollar (U$) a foot, minimum 4 ft. plus a buck or so for freight. Two inch samples are available free, postpaid.
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