Gas Engine Fuel Clunk
02-12-2010, 05:39 PM
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Gas Engine Fuel Clunk
I am looking at setting up a plane with a small displacement gas engine and I'm trying to pencil it out to come as close as possible to the weight of a glow set up. One area were I can save on weight is on a smaller fuel tank but I am concerned that the clunk will not work properly in a smaller tank as the yellow fuel line I have is quite a bit stiffer than the silicon type glow fuel line. Is there a more flexible gas type fuel line avalible that would allow the clunk to move freely in a smaller tank?
02-12-2010, 05:55 PM
#3
RE: Gas Engine Fuel Clunk
I tried that same fuel line from Tower about 3 months ago. DO NOT USE IT. It will swell in a short time. Go to a place that sells chain saws...or Echo products, they got good line. Capt,n
02-12-2010, 06:23 PM
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RE: Gas Engine Fuel Clunk
Thanx for the suggestions guys. I will have a look at some fuel line at my local small engine shop. If I remember correctly I bought the yellow tygon type at the hobby shop because i thought it was the most flexable but I don't know what kind their black fuel line was. I guess maybe their isn't any gas rated line as flexible as silicon type. Any ideas on what the best size and shape of tank to use in order to have the smallest tank with good clunk action?
02-12-2010, 06:43 PM
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RE: Gas Engine Fuel Clunk
I use a Walbro brand felt clunk. I have seen other brands available but I like the quality of the walbro the best, I have never had any trouble with them. I see alot of people using a filter for glow fuel with gas, which is ok I guess, but the mesh of a glow fuel filter is not fine enough to properly filter gasoline.
I use the same tanks that I use for glow fuel. My decision about size and shape is usually based on the shape of the model and space allowed for the tank rather than the type of fuel (gas/glow).
Ace hardware also sells the tubing for gas line use but i think the yellow stuff at the hobby shops is more flexible. Black neoprene is very flexible but IMHO it is not durable and doesn't last long.
I use the same tanks that I use for glow fuel. My decision about size and shape is usually based on the shape of the model and space allowed for the tank rather than the type of fuel (gas/glow).
Ace hardware also sells the tubing for gas line use but i think the yellow stuff at the hobby shops is more flexible. Black neoprene is very flexible but IMHO it is not durable and doesn't last long.
02-12-2010, 08:01 PM
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RE: Gas Engine Fuel Clunk
ORIGINAL: Carpilot
I use a Walbro brand felt clunk. I have seen other brands available but I like the quality of the walbro the best, I have never had any trouble with them. I see alot of people using a filter for glow fuel with gas, which is ok I guess, but the mesh of a glow fuel filter is not fine enough to properly filter gasoline.
I use the same tanks that I use for glow fuel. My decision about size and shape is usually based on the shape of the model and space allowed for the tank rather than the type of fuel (gas/glow).
Ace hardware also sells the tubing for gas line use but i think the yellow stuff at the hobby shops is more flexible. Black neoprene is very flexible but IMHO it is not durable and doesn't last long.
I use a Walbro brand felt clunk. I have seen other brands available but I like the quality of the walbro the best, I have never had any trouble with them. I see alot of people using a filter for glow fuel with gas, which is ok I guess, but the mesh of a glow fuel filter is not fine enough to properly filter gasoline.
I use the same tanks that I use for glow fuel. My decision about size and shape is usually based on the shape of the model and space allowed for the tank rather than the type of fuel (gas/glow).
Ace hardware also sells the tubing for gas line use but i think the yellow stuff at the hobby shops is more flexible. Black neoprene is very flexible but IMHO it is not durable and doesn't last long.
Bliksem
02-12-2010, 09:56 PM
#11
RE: Gas Engine Fuel Clunk
At your local chain saw dealer or from Horizon or Tower
http://www.horizonhobby.com/Products...odID=SAIG36154 This is a Walbro clunk but they should be cheaper at the chain saw dealer
http://www3.towerhobbies.com/cgi-bin...&I=LXXF25&P=ML
http://www.horizonhobby.com/Products...odID=SAIG36154 This is a Walbro clunk but they should be cheaper at the chain saw dealer
http://www3.towerhobbies.com/cgi-bin...&I=LXXF25&P=ML
02-12-2010, 10:58 PM
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RE: Gas Engine Fuel Clunk
Back about 2 years ago, when I heard that Hayes seemless black neoprene was the ultimate solution to using Tygon in the tank, I changed 5 tanks over to Hayes, not DuBro, which I understand has a seam and splits. Is Hayes really that bad ? Does anyone know the full story on using Hayes, which is supposed to be a superior grade of neoprene ?
Ed
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02-13-2010, 04:11 AM
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RE: Gas Engine Fuel Clunk
I use viton with dual clunks on my fill and pickup lines, and Hayes #249 neoprene with a 90-degree fitting for the vent line. With postage, the viton cost me about $5 per foot, but no more fuel system/plumbing problems. I wish viton could also cure brain farts and dumb thumbs. LOL.
02-13-2010, 11:18 AM
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RE: Gas Engine Fuel Clunk
Been using Hayes black seamless neoprene tubing for all my in-tank suction lines ever since Ralph (Antique) told me about it about 5 years ago and have never had a problem.
Karol
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02-13-2010, 12:03 PM
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RE: Gas Engine Fuel Clunk
Karol have you compared the Hayes neoprene line to any others in regards to flexibility? If it is less stiff than the others thats what I am looking for.
02-13-2010, 12:53 PM
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RE: Gas Engine Fuel Clunk
How flexible do you really need? Too flexible and the clunk ends up at the front of the tank. The next sound you hear is engine stop. You need to stop thinking like a glow flier. Most experienced gas fliers don't need any more flexibility than required to let the clunk follow the fuel. That isn't very much if you have the right kind of clunk. Heavier clunks don't need ultra flex line such as that used in glow fuel tanks with tiny clunks.
02-13-2010, 02:27 PM
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RE: Gas Engine Fuel Clunk
I have a 14oz tank in my 1/4 scale and its fine with the tygon line on the clunk, but I am trying to rationalize putting a small gas engine in my showtime 90 and I need to take advantage of everything I can to make the gas option pencil out. I would like to go as small as 8 to 10 oz with the tank but I'm concerned that the less flexibile gas line will not allow the clunk to move freely enough in the small tank because the clunk line needs to be so short in a small tank. I would be interested to know what is the smallest tank anybody has used on gas without getting into clunk issues.
02-13-2010, 05:51 PM
#22
RE: Gas Engine Fuel Clunk
Seagull I took a used tank from an old ARF that was around 10 ounces and used the Hayes tubing and a regular glow clunk for my test stand. The clunk moves around easily like if it had silicone tubing. I don't use it in a plane but I'm sure it would work fine if it were. The Hayes tubing has lasted a couple of months without any problem so far. I had read some bad press on it and I am keeping an eye on it to see how long it lasts.
02-13-2010, 06:25 PM
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RE: Gas Engine Fuel Clunk
The clunk in an 8-12 oz tank only needs to move about 1-1/2" in any direction to hit every corner. So how flexible does the line need to be? A good filter, not any of the types used with glow engines, protects your engine and keeps it running. A heavy clunk keeps the pick up in the gas, and a felt filtered clunk only needs to touch the gas to pick it up, while also breaking up air bubbles in the drawn fuel. How many grams of weight is that kind of performance, safety, and reliability worth? Any of the leading types of gas fuel line will suit your needs.
02-13-2010, 07:00 PM
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RE: Gas Engine Fuel Clunk
Thanx Texasbird, thats what I wanted to know. Where do you buy the Hayes tubing? While I do not like to use anything that is heavier than it needs to be on a performance plane, I will go with the heavier walbro type filter clunk as I do believe this may make for a more reliable running engine. One of my least favorite jobs when putting a plane together is plumbing the tank because it is easy to get the clunk line not quite right and that can lead to major trouble at the field.