The instructions with my MVVS 1.60 say to use a felt wrapped clunk, as used in the tanks of weed-wackers and chain saws.

I have obtained one from my garden appliance dealer. It has a black plastic outer encasing a thick off-white felt inner.

The instructions say this type of clunk helps prevent bubbles getting in the line causing fuel feed problems due to momentary exposure to air during manouveurs. The felt is also supposed to help filter the fuel.

Does anyone have experience (good or bad) with this type of clunk in an R/C aircraft? I'd like to know before fitting the tank in my bird.

I got one, it was to big to go in the tank. [X(]

fiery,

I had one that came with my tank. Worked fine. After a while I started having engine trouble. Could not keep it running. Cleaned the carb and all was good as new, then it started again. I went through the cycle again and decided an in-line filter was called for. While cutting the fuel line to the carb, I noticed a white powery residue on the inside of the fuel line. That was enough for me. I removed the felt clunk filter, put in the in-line filter and have not had a repeat of the problem. Much later inspections of the fuel line have not turned up any further white residue.

My experience anyway.

Bedford

I've used them on my gas engines and never had any problems. Not even air bubbles or foam.

Enjoy,

Jim

I had the fibers from one clog the carb screen on my BME. It looked like wet sand in the screen. Many people use them w/o problems, but I won't. I really don't see the need for one, anyway. A good in-line filter works fine. I use Sullivan Crap Traps w/o problem.

I've used them for years on 5 different engines with no problem. Much better than the bare clunk.

Several years ago I used the ones from B&B Specialties. http://bennettbuilt.com/page5.htm
They worked fine and I had no problems. At some point I started filtering all of the fuel before it went into the plane's tank by using an automotive type fuel filter. At the same time I started using the clunks that came with the tanks. Using this method I have never had a stopped up carb screen. If totally clean filtered gasoline goes in, why do you need an in tank filter?

Ken

I use felt clunk filters from B&B. Never found dirt or fibers in the carb. I also have an inline filter on my one gallon gas container. Aren't the better bourbons double filtered?....

I have been using the Walbro filter clunks on my gas engines for several years with good results. You never have to worry about air bubbles and you can empty the tank completely without leaving even a drop of fuel. The only problem that I ever ran into was that I sometimes had a lean run after the filter had been in service for a while. On the Walbro filter clunk, there are actually two filters. In addition to the felt filter, there is a very fine sintered paper filter at the filter outlet. This paper filter is so fine that it gradually clogs over a long period of time. To maintain high flow rates you can remove the paper filter and use only the felt filter, or you can poke a few holes with a model pin in the paper filter to keep any felt fibers in place. An additional plus is that you nver have to worry about foaming fuel in the tank from vibration. The felt separates the air and delivers only liquid to the engine.
I have used these filters on gas engines only. I have heard some complaints about white powdery residues when these filters are used on glow fuels.

Interesting replies. I think I'll give the felt clunk a go. It fits easily into my Sullivan 14 Oz round tank, but wouldn't into the Hayes Slimline 14 Oz tank I had lined up.

I am using a nice in-line filter between tank and carb. That should deal with any felt fibres.

I found it after nosing around at my friendly local motorcycle shop. It has a crystal clear heat resistant body with an ultra fine filter mesh. It is used on scooters and the like, and has a much larger surface area than typical model engine filters. It looks to be well made - it is made by in the USA in Ill. by Plastisonics, if I can read the brand correctly. Cheaper than your better model filters too!

They also do a smaller in-line filter with a "sintered brass micro-ball" type filter media, like Du-bro use on their "filter" clunk. I bought it as well, but I am a little wary of it though - I am always scared a little peice of brass will break free and cause a blockage somewhere, or worse [:'(]

I have any adverse experiences I'll post again. Thanks to all who posted

fiery

Ran a small motor shop for 35 yrs. and felt filters have been used in chainsaws since long before that.

So Gord:
I take it you've never observed this "so-called problem" of felt clunks clogging up the carb screens with pieces of fiber? Forty + years of felt clunks sounds to me like the data has been collected...

Out of the Blue, "a Q. from a newbe with Gas" could i use a glow engine fuel filter for gas engines?

Thanks
Moe

I tried one which worked well for a brief time but it got clogged up and staved the engine of fuel. Since then I have installed an industrial type gasoline filter on my fuel jug and an inline filter in the fuel line to the engine which has worked flawlessly.

I think the real benefit of a felt clunk (especially with gas engines where we use tygon tubing and it can't flop) is that in a diving vertical attitude the engine does not suffer fuel starvation and flame out. Anyone else use them for this purpose?

I don't know if that would work (after doing a little testing today). When emptying my tank with back into my fuel jug, once the fuel reached the level of the top of the clunk I started getting very fine air-bubbles in the fuel line... I believe this would cause a lean condition. I'm not sure what the dynamics of having one large air bubble in the line are... anyone know? Would the bubble be "Passed" by the carb very quickly?

The big drawback for me is that the felt clunk left a lot of unusable fuel in the tank as it would draw in air at the same time as the fuel as soon as the a small piece of felt was exposed. I went with a very large and heavy simple clunk with a 3/16" ID.

beepee, were you running gas or alcohol?

Bill

sillyness, that is just the opposite of what you would expect to see when using a felt lined clunk. Normally if the whole clunk has been wet with fuel it will continue to allow you to draw untill the tank is empty. Were you putting a real fast draw on the fuel?

Ed M.

I have also run the metal Walbro clunk for a long time in many gas planes with no problems. My findings on using all the available fuel in the tank are opposite of what sillyness has experienced. Recently I landed and taxied back to find zero fuel in the tank, my felt clunks have always pulled every last drop of fuel from the tank. This has been my experience with the engine running, I do not fuel or defuel through my felt clunk, I use a second clunk in a three line system for that.

Bill,

Gas. Feeding a Quadra 42.

Bedford (beepee)

i just recently started in gas and found at one of the wedie shops the ceramic clunks. there white in color. very similier to the brass ones.