I am building my first kit. It is a piper cub j3 40 size. Anyway i'm using a pitts style muffler and the pressure hose for the fuel tank that is connected to the muffler will be behing the cowl. The fuel tank i have has an overflow hole in it that i could hook to some fitting on the bottom of the plane but i can't seem to find that kind of fitting. That is what i need your help for and help would be greatly appreciated. Thank You

Look for a fuel Dot! That may be what you need
.Larry

Bostonba, the tank needs to be in one of two configurations, A two line where the clunk feeds the carb and the "vent" is used for presure from the muffler. This is the most common on smaller size planes and what I use mostly.

The other is athree line setup where you have a vent line seperate from the muffler pressure line and you use the vent for a fill. Depending on the engine, you will plug or leave this line open The differece here is whether the engine is a pump engine or not. If it is a pumper, not a Y.S Pumper, then you leave the vent line open when flying.

All that sounds confusing and doesn't apply to your setup.. Make sure your tank is setup so the center line of the tank is even with the spray bar of the carb. Ipull the line off the carb and fill through that line. I also pull the line off the muffler and route it back to the jug. That way, I minimsize the pick up of moist air into the tank. You can just put a catch pan under the muffler and when fuel flowns out of the muffler, your tank is full.When you see fuel going back to the jug from the vent line, with my setup,or exiting the muffelerinto the catch pan witth the other, reverse the pump for a crank or twofor amanual pump or a secnd or so for an electric. Pug your lines back to the carb and muffleif you removed it and you are ready togo

The fuel dot is just a"T" fitting that goes into the carb line. You may flood theengineusing this setup if itisn't apumper.IF youuse the three line setup, you can pump until the fuel comes out of the muffler and then plug the dot line. Again,this setup may flood the carb when fueling.

The two line setup is the simplest and less likely to cause you problems when startingout.

Don

I've tried and don't like the three line set up. That just me though. Leave the third fitting plugged and get a fueler valve and use the 2 line set up. Hook this in line with the carb. In the GP cub you should be able to see the fuel tank to know when to slow down fueling and let a little run out the muffler.

Acually I've build both the 40 and 60 GP cub and found that enlarging the opening around the engine to be the best way to fuel it, unless your planning to enter the plane on anational level no one would ever notice. Enlarge the cowl around the carb enough the reach the carb nipple and fuel line and grab it with a pair of hemostates. Of course I'm running 4 strokes mounted sideways. It kinda sounds like your running a 2-stroke upside down in which case go with the fueler valve. I did that on my first 40 sized cub and put the fueler valve right smack in the middle of the top of the cowl were the real cub is fueled

The easiest set up for you may be to run a 2 line set up...the vent line will go to your muffler, and the fuel line could be routed out the bottom or side of the cowl in an inconspicious place. Use a small piece of brass tube and bend a small "U" shaped piece. Use this piece to splice the fuel line, so that you can unhook the fuel pick up line outside of the cowl to fuel the plane. Just watch for fuel running out of your mufler when you fill it up, then hook your lines back together. Good luck with it! -Craig

Boston ba745, if I read your original post correctly then you are looking for a way to tell if your fuel tank is full when all the pipes are behind the cowl. I think the simplest way is as campgems explained and that is to crank the fuel pump handle until fuel comes out of the exhaust then back off 2 or 3 turns of the fuel pump. I do things this way, using a three line setup so with the exception of the fuel dot (which is easily accessable) there is no need to unplug any of the other fuel lines. I also count how many turns of the hande it takes to fill the tank, for instance an 8oz tank tanks 28 full revolutions of the fuel pump handle, so by 25 I start to turn more slowly.

If you are using a two line setup with a fueling valve I guess the same would apply.

Are you using a 2 or 3 line fuel tank?

thanks everyone for your advice. i have installed a fueler valve and i think i will go with the wait till you see fuel come out of the muffler method. thanks alot