flybyjohn

My Feedback: (2)

In that case you can buy a cowl mounted fill plug. This mounts on the cowl and is in line with the fuel pickup tube. The exhaust line always stays connected to the muffler. When you fuel, a connector will go into this valve and shut the fuel flow off going to the engine and the fuel will flow into the tank. When you pull the connector out it will open back up the flow from the tank to the engine.

If you don't want to purchase this filling valve, you can just put a Tee connector in line from your tank to your carb. Run a tube from the tee to outside the cowl somewhere and put a plug in it. When you want to fill or unfuel just shut the carb all the way closed and unplug the tube and fill or unfuel and then replug the tube. With the carb all the way closed, very little fuel will go into the carb when you pump fuel into the tank. You will then only need two lines to the tank.

DUNNJR4

My Feedback: (1)

Dont you need to remove the exhaust line for the overflow?

flybyjohn

My Feedback: (2)

I don't remove mine, I know how many cranks it takes to fill from empty and then when I get close to full I slow down, If I do get a little fuel in the exhaust, it just blows out when I start it. If your engine is in a position that the fuel from the muffler can flow into the cylinder then you may have to do something different so you don't get a hydrolock situation.

You may have to scratch what I just said, my muffler sticks out of the cowl so I can see the tubing going to it. If your exhaust tube is inside the cowl, you will not see when the tank gets full. I don't have a solution for this situation.

DUNNJR4

My Feedback: (1)

Is this what i want?

DUNNJR4

My Feedback: (1)

a dubro kwik- fill fueling valve glow? im looking at it at tower hobby.

charlie1960

what your looking for is called a fuel dot.

Sport_Pilot

The various fuel filling valves have a habit of leaking or clogging.  I would also use fuel dots if filling from a closed cowling.

DUNNJR4

My Feedback: (1)

If i use that do i need to unplug the line from the muffler that is the overflow. I cant take that on and off easily because that hookup is under the cowl also.

Sport_Pilot

I thought we were using the uniflow setup this thread has been discussing, if so the muffler would not be the overflow. We need to know how you plan to set this up.

DUNNJR4

My Feedback: (1)

I cant get to the line for the muffler. Ive been trying to figure out if i can run a fourth line as a seperate overflow. I would have a line to the the muffler, a line to the engine, a seperate fill line, and a seperate line as an overflow. i have both a fuel dot and a Fuel valve. so what i want to know is, what is the best way to set up my tank.

pt19 flyer

My Feedback: (1)

hi jaka
got a question, have used the 3 line system before and do not remember any real problems with it, seemed to work fine from memory.
however, now I have a os fx61 with a 3 line take setup and haveing major problems with it.
from memory I capped the vent tube and one clunk ran to the carb and the other ran to the muffler pressure fitting.
with this setup a real problem, engine when it starts continues to want to run backwards. eventually I can get a forward run with great difficulty.
with the above connections the engines when it does run runs backwards. seems to be in a flooded condition.
finally I changed connection and plugged one fo the clunk lines, the other clunk to the carb and the vent to the mulller pressure connector.
this was at the end of the day but I did succeed in getting the engine to run in the forward direction. only one trial run here at end of day.
will see what tomorrow holds.
your opinion and thoughts here.
I have pulled the carb and cleaned it along with all new tubing in t ank and to engine. using os 8 plug and fuel 15% nitro castor and synethetic 18%.
going to add 2% castor to this fuel.

thanks
pt19 flyer
joe

Azcat59

Joe, I think your clunk line connected to the muffler is blowing air bubbles right next to the carb klunk. If you want to use two klunks, use the one for fill and unfill only, plugging the line for flying, and run the vent line from the muffler to the very top front of the tank, as far away from the carb klunk as you can get it.

I use a third line system often, but I make the fill/unfill line out of 1/8" aluminum, and run it to the rear bottom corner of the tank, where it stays out of the way of the carb klunk. And plug this line after filling. Also, on the carb klunk line, don't run it up against the rear of the tank, leave it about half or three quarters of in inch short of the rear. I won't go into why this is good, but trust me, it is, and helps keep the engine from loading up on takeoff acceleration.

Clair Sieverling

pt19 flyer

My Feedback: (1)

thanks Clair for reply
this is the way I had it on my last run. I have struggled with this for the last 7-10 days. plane had been hanging for about 1 year but I had used after run
oil in it when I hung it up. after all this checked manual and they stated at one point <DO NOT USE AFTER RUN OIL IN THROTTLE> bad on "o" rings.
had not seen it before and have used after run in all of my glow engines in the past. in the past I had always plugged the vent and ran one clunk to the carb and
the other to the pressure vent on muffler. I had flown this model in the past I think with that setup but currently is not working as I remember. it was said that this made
the tank less sensitive to changes in fuel level and the air above the fuel in the tank with both clunks below the fuel in the tank.
does not work now however for some reason. may be my memory is failing me at 82yrs old, could this be my problem? ha!ha!
so on my last attempt of the day I did change to plugging one clunk, one clunk to carb and vent to muffler pressure tap. did get it running this way.???? was looking at a flooded condition and reverse running by the old setup.
will definitely give your setup a try with the aluminum tubing to the rear and to one side of the tank and see what happens. like the 3 line
for fueling and defueling at end of day.

will see what the next attempt produces.

many thanks for reply and suggestions

pr19 flyer
joe

pt19 flyer

My Feedback: (1)

hi flybyjohn
I have a similar problem with an os fx61 using the 3 line system. with one clunk to carb and one to muffler and vent plugged the motor is in an flooded
condition and when it runs it runs in the reverse direction. will not run forward. I have use the 3 lines in other planes and with other engines with absolutely
no problem, you might say perfect. but with the os fx61 this is not the case. had been hanging for about a year and I do not recall any problem in this regard.
could this be a problem in the os 61 and 91 series?
did you go back to the old 2 line setup on you 91?
I finally got mine to run on the last attempt of the day by plugging one clunk, one clunk to carb and vent to mufflet pressure connection.
had a short run here but only tried it once, will see what the next attempt holds.

thanks and happy flying
pt19 flyer
joe

1QwkSport2.5r

I've tried using a 3-line setup on an ST S90, K&B .65 and Jett .35. Most often, there is too much muffler pressure. After a WOT run, dropping back to idle causes the pressure line to the muffler to fill with fuel and sometimes that fuel is forced into the muffler thus getting spewed all about. I quit using 3-line fuel tanks. Bladder tanks are the way to go but are expensive. Regular fuel tanks using 2 lines works fine. You just need to isolate the tank to prevent bubbles.

jaka

Hi!
That the Engine runs backwards has nothing to do with how the tank is set up. It only means the Engine gets too much fuel.

The Uni-Flow system with two clunks Ed Smith and I have talked about is the next best way of fueling a glow/diesel Engine ,best way is using a Tettra "Bubble less" tank.

The Uni-flow tank must be set up with the two clunks running parallell with each other, one fuel line a few centimer shorter than the other.
The Picture you showed with one clunk and a soldered tubing on top of the clunk is you risk air going into the carb fuelline.

To have the Uni-flow system work you must mount the tank according to the "tank-mounting-rule", this is as important as with any other tank system. If you follow this rule you will have a tank system slightly superior to an ordinary "two-line" system.
I personaly use it in all my airplanes ,be it pylon racers as well as in sport and scale planes, four-strokes as well as two- strokes (In Q-500 pylon here in sweden Tettra Tanks are not allowed).

pt19 flyer

My Feedback: (1)

hi flybyjohn
have a similar problem with my os fx61. been hanging for about 1 year and I do not remember any problem with it.
however now with the 3 line system it is continually in a flooded condition and insist on running in reverse. had one clunk
to carb one clunk to muffler and overflow capped. have use this system with enya, webra and others with good results.
not true here however. on you os fx 91 did you go back to the two tube system. I have struggled with this problem on and
off for about a week. high frustrated with it. engine has no more than about 3 hours running time. pulled and cleaned carb,
replaced "o" ring on needle valve. on one or two occassions I did get it to run was very rich regardless of needld valve setting.
so please inidcate the solution you found on your 91 problem, may also solve mine
had attempted a previous post on this but apparently did not go thru, don't see it, so try again.

thanks and happy flying
pt19 flyer
joe

aspeed

I have used uniflow tanks on control line planes with good results on suction. With backplate pressure it is better to have the end of the tube anywhere but in the fuel. I would think muffler pressure to a less extent would be better out of the fuel as well, so it doesn't somehow come back in in some strange situations. (like power off dives, just working on it or whatever) I have always had the muffler pressure on the top vent tube. I never used 3 lines yet (hate cowls) but resting at the bottom like a clunk seems ok for fueling and draining the tank if it is plugged. The fuel that always seems to get in the muffler and floods the motor, I always tilt the plane and pour the fuel out, and fill with the piston over the exh port. I have had fairly good luck with these ways. And PT 19 flyer, have you tried blowing through the needle valve nipple and shutting the needle? It should close off completely. It should be able to get lean if that is working right. Maybe the muffler is just filling up with fuel while filling, and not draining out due to maybe the exh. outlet not pointing down or for whatever reason. Also as I said, I put the exh pressure tube on the overflow, not the submerged clunk. It is an easier fix to at least try.

Jim Thomerson

The uniflow tank was invented by Edme Mariotte, of Dijon, France, back in the 1600s. Google mariotte bottle, or mariotte syphon for an explanation. A friend has good luck flying control line stunt airplanes with flexible lines to a combined pickup + uniflow clunk. We generally fly until run out of fuel, so routine defueling is not an issue. We do use an overflow, which is capped off in flight.

aspeed

On suction, right? No muffler pressure?

Jim Thomerson

With open to the air, I use a one way valve in the uniflow to stop syphoning, and mitigate effects of outside pressure change. With muffler I don't use a one way valve to the uniflow. With small engines on crankcase pressure I use a one way in the pressure line to the uniflow. I generally fill through the uniflow line, uncapping the overflow.

flybyjohn

My Feedback: (2)

pt19 flyer, sorry haven't looked at this thread in a while. On my os 91 I removed the three line settup because the pressure at full throttle was so much more than at idle and the fuel was pushing back into the muffler when going from full to idle. I just went back to the 2 line settup and put a different carb on and it seems to run better with the different carb. My thunder tiger 46 pros and a CS 46 engine I have work wonderfull on the 3 line uniflow system. I cannot tell the difference in engine performance from full tank to empty except the plane flies a little lighter.

pt19 flyer

My Feedback: (1)

ok flybyjohn
what carb did you go to? the few times I was able to get the fx61 running it is a powerful engine, lots of thrust,
but temporary in nature. I guess I will go back to the two line setup and see what happens.
this is an old engine but new in terms of use. probably less than 3-4 hours running time and as I said I do not
remember this problem when I was flyhing it with the 3line setup a little more than a year ago, been hanging idle
in basement. this is on an old lanier caprice from the mido-60's great flyer, but plastic and won't take too well]
to grass landinds does well on asphalt.

thanks again for ur input on this
happy flying
pt19 flyer
joe

flybyjohn

My Feedback: (2)

I put a super tiger 61 carb on it, however the os engines had decent carbs and your fx carb might be fine. Mine was the rear needle carb with the metal mount. They were supposed to be trouble on the 91 engines. I started with cutting it off and mounting it to the firewall but still had problems so I then put the super tigre carb on and it runs but sounds like crap in the air. I think I need to strip down the engine and see if the insides all look good.

Sport_Pilot

This is typical of the uniflow setup, especially with a short muffler to tank line. To fix this make the muffler line longer, or include a check valve. ON my engines I will add a loop in the muffler line and it will only do this when the tank is full, so I just keep it full throttle for a couple of minutes. IMO it is really no big deal anyway. It is more important to me that the engine runs consistantly from full to empty tank.