Does anyone know where I could get or how to make a floating clunk for Gas?

You do not want a floating clunk, in order to work the clunk must sink no matter what attitude the tank is in. Any clunk should work as long as you use gasoline compatable line.

I understand this is a weird (maybe stupid) request. I am using around an 80oz tank for a long haul. I am concerend that when the tank is full, it will create pressure on the line from the fuel above. Tward the end of the trip, there is no pressure because the tank has no fuel, causing it to lean out. Maybe I'm all wet, maybe the pump in the carb will take care of it.

A floating clunk (not a good idea for other reasons) wouldn't make any difference in pressure at all. It's the head pressure created by the level of fuel above the carb that's important and it doesn't matter how the head pressure is created. In other words, your floating clunk will produce the same head pressure at the carb as one at the bottom of the tank with a given fuel level. Fluid Dynamics 101.

If you are using an engine with a Walbro or similar carb I think you can probably forget about it. They have an internal fuel pump and pressure regulation system that eliminates head pressure changes from the tank level (and attitude).

If your engine is not using the Walbro-type carb then you need to get and learn to use an after-market pressure regulation system such as the Cline or possibly the Perry/Varsane. An 80-oz. tank with a non-pressure regulated fuel system is most likely gonna be trouble.

hey bud,,,sounds like your try'n to re-invent the wheel...just go with a standerd material and youll be fine..Rod

Ya, I now agree with you. I took a 36 oz Ketchup bottle, stood it up on end, and ran 1 hour with no problems what so ever. I guess I should not think. Gets me into trouble.

Thought I would put this here as it has to do with a clunk per se. I thought it would be prudent to re-plumb my fuel tank as the yellow gas line was hard and not floating to the bottom as I would like it. I grabbed some line from the supply hanging on the wall and promptly re did the tank. Went to the field and flew for about 5 minutes when the engine flamed out Needless to say I didn't make it back to the landing area. I was lucky. The grass was high where I landed and the ground was soft. What the he..? Was the low end too lean?, did the ignition die? Pancaked it and did a little damage, nothing serious thankfully. I am taking the fuel out of the tank while wondering what happened and I can't get anything out of the tank Long story short, the fuel line I used to plumb the clunk is a larger ID that the other line I have. It actually slipped off of the stopper and the engine could suck no fuel. Dag! The fuel line that has worked fine forever has writing on it that says, "GO 1480." This may be old hat to you guys, but it almost cost me a 35% plane for my ignorance. I now have the stainless wires on the tank lines and make sure the gas lines say "GO 1480"

Use Aerotrend easyflex fuel tubing + steel clips available at Home Depot in the plumbing area.

Can you post a picture of the clips? Are they stainless for gas?
Thanks_bob

They look plated to me (zinc?). I can't do digital pictures. Home Depot...plumbing section.....little drawers......lots of parts like o-rings etc.....in little plastic bags....different diameters available....plumbing band clamps.

I use the smallest nylon tye-wraps on all the lines in the tank including the clunk. Also use them on all of the lines external to the tank. Available at Radio Shack, Lowes, Home Depot, Fry's, etc. Never had a problem with a line coming off. Good for gasoline or glow fuel.

Ken

I almost found out the hard way that fuel tubing for gasoline is a lot less forgiving than that for glow fuel.

I did the plumbing in my new MW Extra 300 using the black gas tubing that came in a "gas conversion package" complete with s/s tying wires, and all worked well for awhile.

A few months later, I fire up the engine at the field for a flight and notice that the engine is running erratically. Finally, after several attempts to get it running properly without success I call it a day and pack up.

Back home I inspect the fuel system , only to find that the black tubing in the tank has split along it's seam and the clunk is rolling around in the tank. Moral of the story....use only the best tubing available for gasoline.