qcrcbill

Hey Guys! I'll be plumbing my J-3 ARF soon, and am in a quandry re. fuel valves and Fuel Dots? Could someone in a few sentences please explain how to hook up a Fuel Dot and Fuel Filler valve? I'm curious about end of day draining, and overflow after filling. There's not much room under my cowl for fingers pulling off tubing! Thanks a bunch as always! Bill

staggerwing

My Feedback: (5)

If you want to use a fuel valve, look at Slimline, Robart and Hughs RC. They have fillers that won't develop leaks. Most guys who fly with gas engines use fuel dots. You can use a two or three tube system. With a gasoline engine, the carb keeps the air from getting into the fuel line so that you can pump the fuel in and out of the tank through a "T" connector in the carb line that goes to the fuel dot. On glow engines I use a three tube system with two klunks in the tank. One for feeding the carb and one for getting the fuel out of the tank. I put a fuel dot on the tube that is used to get the fuel out of the tank.

Geistware

My Feedback: (16)

Basically a fuel valve is a fuel dot and "T" built together.
I would recommend the dot and "T" since there are no parts that can fail.

qcrcbill

Interesting. So a "dot" is a plug? yes folks....I am a beginner...doesn't it show? thanks again. Bill

DOH_Blk_Adder

whos J3 Bill? I just put in dots last night in my Graupner Cub came out kinda sloppy then I discovered there is a dot assembly that has a coller for the hose that you affix to the cowl. the dod is then plugged in from out side the cowl .. much cleaner way than just dots alone.... back to the hobby shop for me

tommy157

My Feedback: (1)

If you want to use a fuel valve, look at Slimline, Robart and Hughs RC. They have fillers that won't develop leaks.

Wrong... or at least the Robart I had leaked back to muffler when filling sent it back and it's been a month and no replacement..went to Dots there fool proof

MinnFlyer

My Feedback: (4)

Here are a few images of Fuel Dots for ya.

RCJake-rcu

My Feedback: (7)

If you don't want to mount the dot to the cowl, get an angle bracket made by Sig, mount it to the fuse, mount the fuel dot to the bracket and make a hole in the cowl to access the fuel dot. Makes it easier to remove the cowl later.

gwk

Where does the over-flow fuel exit when filling the tank?

Thanks,

Greg

MinnFlyer

My Feedback: (4)

It comes out the vent line that is attached to the muffler. You either want to disconnect it, or keep an eye on it (Or just wait for fuel to come spilling out of the muffler LOL)

FHHuber

I prefer a dot to a valve. The valves have seals which can fail. The dots are virtually foolproof.

A simple dot setup would have a 3rd line to the tank (this is why Sullivan and DuBro have the 3rd hole...) going to a tube which either S trns to the tank bottom or has a second clunk.

You simply fuel and defuel via the dot. The dot itself is just a plug for the fuel lint and then there is the fitting thatis screwed to the aircraft side. you have about 3 to 6 inches slack line you can pull out with the dot... and its easy to hook to the pump.

Fuel with the throttle CLOSED. This guarantees you won't pump fuel past the needle valve and flood the engine. (you still have to watch for the fuel inthe muffler line... just as when fuelig from the neddle valve line as is typical for 2-line setups.)

Very simple... very clean and no problems with the crazy valves seals. (which always seem to leak on me within 6 tanks of my installing the valve...)

DBCherry

My Feedback: (4)

I stopped using fuel fillers after I installed and used my first dot. I wouldn't go back.
Dennis-

Eindecker_pilot

If using a 3 line system with fuel dots, does fueling with the throttle closed prevent flooding on a gas engine carb? It seems that once the tank is full, fuel will want to come out of both the vent line & carb line...

Thanks in advance.

ho2zoo

My Feedback: (5)

I have three planes with the Dubro fuel valves and they work pretty well. Not perfect, but acceptible. They will occasionally stick in the 'fill' position (with the center post stuck in) which is a pain in the rump. I just keep a small screwdriver handy to pop it back out. After about 5 years I usually have to replace them because of leaks.

All in all, a fuel dot is probably more robust, but more fuel line to install.

J_R

I, too, prefer the fuel dots.

A couple of other thoughts.

Keep an extra tank in your flight box with 6 inches of tubing attached. Pull the line from the muffler and direct it into the extra tank to catch the overflow. There is not much point to pumping fuel out on the ground. In the case where I can not get to the line, I put a tuna can under the muffler to catch the overflow.

If you do use fuel fillers and the seals fail, rebuild kits are available.

Eindecker_pilot

What's the risk of flooding a gas engine if using a 3-line (vent, fill, carb) set-up & a fuel dot? My concern is if I use a fuel dot on the fill line and fill the tank to the point where fuel dribbles out the vent line, fuel will also go into the carb line. Is there significant risk of flooding the carb then? My carb is side mounted such that the opening is at the 9 o'clock position. Are gassers less susceptible to this than glow engines?

thanks!

Kmot

My Feedback: (24)

Just getting back into planes after a long hiatus. I used to pull the line off the carb to fill the tank and watch it overflow out the muffler pressure line. I bought a Great Planes 'fueling valve' thinking that was a better idea but now I am concerned about possible leaks so I like the idea of fuel dots better. Never heard of them before and it looks simple enough but I am confused by the picture posted by Minnflyer. If you use 'one' fuel dot for fueling and still need to pull the muffler pressure line for overflow, why are there 'two' fuel dots attched to the side of the cowl in his picture? Is there a way to have another fuel dot as overflow instead of pulling the muffler pressure line? How ould you plumb that setup?

Thanks!

J_R

The picture of the two dots on the cowl is probably for a setup with a pumped engine that does not require pressure from the muffler. The second dot is the overflow, since no line exists from the muffler to the tank. .

Kmot

My Feedback: (24)

I just found the answer on Slimline's website.

hookedonrc

I use fuel dots on every plane that has enough room. My Magic 300 Extra, and Something extra do not have fuel dots. Overall I like them, and use a second clunk in the tank for the fill/drain from the dot itself. I do recommend one thing, I take the exhaust pressure line off for filling on non-inverted engines. It seems to flow out of the muffler better if the engine is mounted at 90 degrees or inverted. I do think catching the fuel from the pressure line is a good idea. I am planning to get a small jar with a resealable lid and then dump it back into the fuel jug at the end of the day.

ml3456

Walbro carbs shouldn't flood from filling because the pump/check valves opens on vacumm, not pressure.

wings

I just got a space walker a couple weeks ago, it has a cowl. I bought a three way filler valve. That was a swift waste of 12 bucks!

It didn't work right from the beginning.

I have been flying it without the cowl. Where do you get fuel dots? It sounds like a winner. Are the available at Tower Hobbies?


Wings

J_R

There are probably more sources for fuel dots than can be listed. I believe Dubro makes some of plastic. I like the ones that Central Hobbies sells.

Dsegal

> and use a second clunk in the tank <

What is the benefit of using a second clunk rather than a rigid tube bent down to the bottom of the tank? Does the second clunk risk tangling with the fuel pickup clunk?

hookedonrc

I use the separate clunk and use a zip tie to band them together to keep them from tangling. Be careful to not pinch the fuel tubing closed. The only benefit that I see is that you will get to the back lower part of the tank when de-fueling if it is tipped at an angle like taildraggers are. There may be others.