Inverted Engine
 

My new tocano 40 has an inverted engine. I started it for the first time yesterday. I could not get it to start on it's wheels' engine was too tight. So I turned the plane over and got it started. It was way too rich, but ran tank of fuel through it anyway and then one more. When I turn the plane over with a full tank of fuel, the fuel pours out of the carb, The nose is kinda down hill while it sets on my flight box upside down. Anyway, I did a search here and it seems that inverted engines are not actually a good idea. I'm thinking I should turn it upright. For the second tank of fuel I was able to get it started easily with it on it's wheels.
Dont really want to fool around with loosening the glow plug for starting. What are your opiinions? The engine is a new Fox 45bb, with a single needle carb

RE: Inverted Engine
 

I have one inverted two stroke, a ST 90, all I did was lower the fuel tank below the carb line and I also run a 4 stroke plug in it. I have yet to have any problems with it. I know a lot of people that will run on board glow for them. You can try lowering your fuel tank and this should stop the gas from pouring out of the carb.

RE: Inverted Engine
 

thanks. No on board glow. But does have a remote glow connector on the side, Will play with it some more. Just concerned about how it will act in flight. Will see if there is roomn for to lower the fuel tank.

RE: Inverted Engine
 

That's exactly what you must do lower tank. Center line of tank should be even with or slightly below needle valve of carb.

RE: Inverted Engine
 

Why do you have to use a hotter plug, just because the engine is inverted? To get a easier start? When the engine is running, the right plug is the right plug, inverted or not ;)

RE: Inverted Engine
 

Going to have to take the cowl off for inspection. I also noticed that when it was running yesterday, there was fuel coming up from the spinner and over the upper edge of the cowl, and that can't be right.
I'm still curious about lowering the tank. As it only seems to be lwking when I have it inverted for starting ( the plane that is not the engine) When I invert the plane, engine is in upright position.

RE: Inverted Engine
 

I guess you could say this if you install the motor the correct way(as recommended, right side up). When it's inverted you have more fuel seeping into the motor which if your burning a hotter plug it will burn up the fuel faster which would keep it from flooding. Then you would have to ask yourself, Why use an on board glow system? Remember these motors 2 or 4 stroke were not design and built to run inverted.

Billd76, in your first post you stated that you couldn't get the motor started because it was too tight then you went on to mention that you didn't want to remove the plug to start it. Tight engine would suggest to me that your motor is filling with fuel before you even go to start it. Lowering the tank would prevent the fuel from seeping down at a constant rate to your motor. You can always start the plane inverted and then flip it over and it should stay running unless it starts to flood out and dies which take us back to a hotter plug.

RE: Inverted Engine
 

I have the same problem at times with my Venus 40. It is very easy to flood when priming it which will cause the engine to be very tight if not impossible to turn. I've found I only need to seal the exaust or the carb with my finger and turn the engine over about twice to get enough fuel into the carb to start it. After its primed, it leaks a little fuel when sitting if the engine is not running, but it does not affect it after its running. The fuel you see comming from the spinner is probably fuel that spilled out of the carb before you got it started or while you had it turned upside down. Lowering the tank or mounting the engine at 90 degrees are the only ways I've heard of to solve this problem. If you mount the engine right side up, the fuel tank will be too far below the carb and will probably not draw fuel properly when you get down to about half a tank.

RE: Inverted Engine
 

All good info guys thanks. I pulled the cowl off tonight and with the plane sitting as it should, the full tank is definitely above the carb. Had tad bit of fuel in it and it just poors out of the carb. Will get to the fuel tank tomorrow and see what I can do about lowering. I bought the plane off a guy that built it, but never flew it. Maybe he just put the tank in upside down. When it's upright is it a breeze to turn over, but inverted, huge difference. I took the plane outside and drained the exhaust and any fuel out of the carb, and it was still a bear to turn over inverted. Pulled the glow plug and it turned over fine. I may just resort to mounting the engine upright and leaving the cowl off. Guy told me that it was a Fox single screw carb, but it has a low speed needle too. Who knows I just may have bad "goods". Guy works at the LHS, I do not believe that he would sell me anyting bad. Other than this flooding issue, plane is perfect!!!

RE: Inverted Engine
 

An engine doesn't care which way it's mounted. The operator though has to be aware of a few things. First, the centre line of the tank should be level or slightly below the centre of the carb barrel. With an inverted engine any fuel that drains from the tank through to the carb just dribbles straight down onto the ground. An inverted engine is more sensitive to the amount of priming because it gets trapped in the combustion chamber which can cause a hydraulic lock. Always turn the prop over a couple of times by hand before hitting it with an electric starter. A trap that's not always obvious with an inverted engine is that fuel can sometimes flow back through the pressure line into the muffler because the muffler is then way below the tank. The fuel in the muffler then gets through the engine's exhaust port and floods it. This seems to be the major problem in this case because of having to empty the muffler of fuel.

RE: Inverted Engine
 

I had pretty good luck with an inverted engine after I made a loop in the fuel line.Come out of the tank and route the hose up as high as you can before going back down to the carb.Doing that solved all my running problems. Now if i can just find an easy solution to keep from flying into trees I'll be happy.

RE: Inverted Engine
 

Every time you flip a plane over on it's back the fuel is going to run out of the pressure vent line into the muffler and this can get into the cylender and lock up the engine. Just food for thought. It's been mentioned, the engine doesn't know how it is mounted but the tank should have the center line even with the carb or close to it. The tank position is very important!!!

RE: Inverted Engine
 

Also since you are starting the engine upright in an inverted mounted plane, mount the tank inverted too. That way you lay the plane on it's back and do all of the fueling and starting procedures like normal.

RE: Inverted Engine
 

got to be the fuel tank location. Will work on that tonight. I really love the plane. should be a simple enough fix.

RE: Inverted Engine
 

You might want to check the tank plumbing to, this can cause problems if the lines are not hooked up to the correct outlets.

RE: Inverted Engine
 

Okay, Lowered the fuel tank tonight, cut the about a 1/4 inch out of the bottom of the balsa that the fuel tank used to set in. The aligment looks 100 % better. Plan on re wrapping it in foam tomorrow and maybe being ready to fly by Sunday. Still need to run the receiver wire back through the fuse to the tail section. I think this will work. i also changed the fuel tank plug, Now have metal tubing. The vent tube runs up with a slight S and the fill tube runs down at a 45 angle. Clunk and clunk line look good too.

RE: Inverted Engine
 

Bill,

Sounds good ! You need a camera :D
or Video camera.

Bob


Semper Fi