I am just finishing my first gasser. I just realized I'm not sure on setting up the fuel lines. No pressure line , right? How do you vent the tank so it doesn't spill out when inverted?

I set mine up for 2 lines. One line is a simple vent that I run out the bottom of the fuselage. The other line has a "T" in it at a location that lets me add a side line to a fuel dot somewhere on the front of the fuselage. Put another way, the line to the carb is also the fill line through the "T".

As far as preventing leaks while inverted, the carb suction pretty much eliminates that. What it doesn't prevent is negligible. Nice thing about gassers, you can put the tank darn near anywhere.

Make sure you are using stoppers and fuel lines for gas, not glow.

I'm a gonna get jumped for this, BUT, I'm definitely against a two line system...
Air bubbles, and dirt...[>:]

I'll vote for the three line fill..
One line to the carb with a chainsaw filter (felt type) on the other end in the tank for the clunk..
One vent line...out the bottom on the plane..
One fill line with a fuel dot plug..

My 2 cents worth.

I like the three line also. On the two line system, if you loose the cap for the teed line, your engine will quit.

The best part is the 3-line system always has gas in the feed line to the carb. When you go to choke a cold engine, you don't have to guess how many prop flips are required to bring gas up the line and to the carb. Starting is much more consistent with a 3-line tank.

What I like about the 3 line setup is draining the tank - you only have to turn it upside down or hold the tail up or stand it on it's nose or use two clunks .

Bingo Diablo-rcu, You said it perfectly.

I have a two line system on my two gas engined models which have performed flawlessly during several hours of operation. One line is the vent which exits the bottom of the model, while the other, the feed line, uses a standard clunk in the tank and a fuel dot grafted into it along with an inline filter just before the carb.

My gas pan uses a felt type chainsaw fllter on the pick up line, and a automotive type fllter in the feed line which fills the tank. Is this system okay or have I just been lucky so far.

karolh

There is nothing wrong with your system. Two or three line systems are a matter of preference.
I just like the three line system better, but name of the game is to get the gas to the engine, both will do it.

I have used two and three line systems and the filter in fron of the engine catches any dirt that may get in the lines. What you do want to do for the vent line is to run it higher than the tank, preferably to the top of the plan and back down to form a trap. This will keep the fuel in the tank when moving it around

karolh

Maybe this site will be of some use to you
http://www.wildharerc.com/Downloads/intro.html

Jemo

Thanks for that very informative link. Sometimes we think we know, only to find that we have been stumbling around in the dark.

For instance, I am aware that gas engines are a lot more frugal on fuel consumption than their glow counterparts, but never made the connection that they would therefore not need larger fuel lines. Thanks again.

Teach Me! Diablo, what is it about a 3 line system that keeps fuel in the carb line as opposed to the 2 line? Thanks_bob

On a 2 or 3 line setup. Does the lines that go in the tank have to be the same size? Can the vent line be smaller than the carb line? Any reasoning....


Thanks
Smokey

I don't know of any reason why the vent line can't be smaller than the fuel line, but why go to the trouble of having two different size lines to contend with, plus any cost saving would be miniscule.

Two line systems have always worked for me. Put a good filter on the engine side of the "T".

I put the fill T in the return line to the tank from the primer bulb. A multi-duty 3rd line. Figure a continuous line has less chance of leaking air than the 3 additional joints to put a T in the engine line.

I read a lot of times " put a T " but why when I try to do that I have my spark plug swiming. My engine is a quadra 35 whith a walbro carb. it is inverted on a Extra 300. I used 2 lines
1 to ventilation and 1 to the carburator whith a large line, its get out to the fuselage and then get into the fuselage to the carburator, there I put a join and put and get out fuel.
sorry my spanish-english.