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Old Jul 14, 2007, 11:15 AM
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tower hobbies 46 ABC

Alright where to start. I have a tower hobbies 46 ABC engine. I can get it to idle perfectly and wide open throttle. the problem is when I try to transition from wide open to idle then back to wide open it will die. I followed the break in procedures in the manuel and using 15% on it. please help I am ready to throw the dam thing away. It has never been in the air.
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Old Jul 14, 2007, 01:41 PM
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I had the same problem with my sons TH .46 it turned out to be a tuning issue. This engine will idle well at a wide range of low end needle setting but the transition requires more precise tuning.

Close the low end needle valve and slowly open it while blowing (with pressure) into the fuel intake, the throttle should be at idle or a couple of clicks above idle. As soon as you detect air coming into the engine stop adjusting and reconnect the fuel lines. Get the engine started and adjust the high end and then check transition. If you still have troubles adjust the low end and then the high end and then check transition and loading. You may need to try a little richer and or a little leaner to find the right setting but you will get it. Oh and before you begin re-tuning this engine put a new glow plug in (just in case).

That's my opinion I basically had the same problem until I went back to the basics and quit paying attention to idle; I think the willingness of this engine to idle well is deceiving. Best of luck.
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Last edited by Lightnin; Oct 07, 2010 at 08:44 PM.
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Old Jul 14, 2007, 08:07 PM
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Thank you I have already tried all these things. No difference
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Old Jul 15, 2007, 03:16 AM
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I know this symptom,try to richen the low end in small portions.Then WOT to clear the crankase and test again.Im sure your complaint will stop.
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Old Jul 15, 2007, 12:59 PM
I meant to do that
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Eagle Mountain, Utah
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If you decide to junk it just send it my way. But first maybe you should get the help from somebody at the flying field. I am sure you can get it running.
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Old Jul 15, 2007, 05:29 PM
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Mathew if you need further help we need to know all the details, what plug, prop and fuel you are using. What model and how are the lines plumbed? Is the tank center in line with the carb, above or below?
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Old Jul 15, 2007, 07:27 PM
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I am using morgan fuel @15 % with a 11x7 prop I have tried an os #3 and #8 glow plug. The tank is centered with the carb. As for the plumbing it is just the normal set up with the clunk it the tank to the needle to the carb. The plane is a great plane cessna sky lane 182.
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Old Jul 15, 2007, 07:37 PM
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Also ran it with a 10x6 prop
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Old Jul 15, 2007, 08:03 PM
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Check to be sure you do not have an air leak in your fuel tank this is one of the problems I had to eliminate on my sons trainer that seemed to help with the issue. The fuel tank had a hairline crack. The hairline crack allowed the pressure to fluctuate too much which caused a tuning nightmare. Tighten all of the fittings on the remote fueler and the carb, make sure the carb is fully seated and the O ring is compressed. Check the needle valve carefully and make sure there are no particles in the needle valve and assembly.

I don't think this is an issue but FYI I use enya no 3 glow plugs in all my tower engines a friend recommended them I tried them and will use nothing else now. The OS #3 should work just fine.

The 11x7 is the largest recommended prop size according to tower, this may not be part of the problem but suggests that the motor may not be fully broken in and is getting too hot at WOT. If this is the case every glow plug you have put in the motor and run this way is likely damaged.

In any case the symptoms you describe suggest lean running, if the engine is fully broken in. These engines do take a fair amount of break-in time.

Check and be sure that the throttle barrel is not over rotating at WOT the tower carb will allow you to rotate the barrel past the point where the throat is fully open, this is also one of the things I noticed and fixed when I managed to get my sons engine running right.

If you do not currently use the pinch test setting the high end needle I highly recommend you do so, and if you have not read the sticky at the top of this forum you should. I am assuming you already have FWIW.

Beyond that I can only re-iterate that you should go back to basics and begin with closing the low end needle valve and re-setting the engine as I described above. I'm not trying to talk down or treat you like you are dumb. When I am frustrated with an engine I do the same thing myself even though I may have done it several times already. It just makes good sense to keep going back to the basics when all else fails.

Right now my gut instinct says the likely problem(s);
1. Lean running and or glow plug got too hot
2. particle in the needle valve(s) and or engine
3. Not completely broken in and or tuning slightly off.
4. You just got a bad engine

If none of the above help send the engine back to Tower they are really good about replacing engines.

On a side note, because of an experience I had when I began flying glow, I take every new engine I receive apart and check for metal flakes or shavings it does not matter what brand.

I wish you the best of luck with your engine my friend.
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Old Jul 15, 2007, 08:08 PM
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Just so I don't leave anything out I also switched to a 11x4 prop and the engine really likes this prop. I suspect that after a I use the 11x4 for awhile I may be able to go back to a 7 pitch prop without difficulty.
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Old Jul 15, 2007, 08:35 PM
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Correct me if I am wrong but there is not supposed to be air entering or exiting from the prop shaft. I just did a pressure test on the engine and found this.
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Old Jul 15, 2007, 08:38 PM
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Lightning I live in surprise AZ. Where do you fly? What part of Phoenix?
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Old Jul 16, 2007, 01:41 AM
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I fly at the Arizona Model Aviators field in East Mesa, Meridian and Brown.

I don't think a little pressure escaping through the front bearing is a big deal, I may be wrong but I have had engines leak fuel from the front when they were flooded and had some after-run seep out over the course of a week and found no negative effects in the air. If I'm not mistaken it is a design feature..as the engine heats up the tolerances get tighter.
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Old Jul 16, 2007, 05:17 PM
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The nose leak is acceptable and even desirable, means the front bearing is getting lubrication. Tower engines are okay but suffer from a lot of quality issues. First make sure the carb is seated very tightly against the 0-ring - it likes to suck air in at that location. Also make sure the back plate 0-ring is doing its job too. Check to see it if is sucking air in through the high speed needle vavle, usually a small piece of fuel tubing slipped over the needle will cure this problem. Also make sure the low speed needle has a good 0-ring too. Once all these paths are cleaned up and sealed then do a tune job, pay close attention to the acceleration from idle to mid range. Get that set right and you will have a barn burner of an engine.

Cheers,

Chip
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Old Jul 16, 2007, 10:31 PM
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Joined Apr 2007
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I run into this with a buddy's engine, he had a Supertigre .45 ABC
It ran great for me when I owned it.... I sold it to him and he could never
get it to run right???. He brought the plane to my house and we fired it up and it ran great. He took the plane to the field and it wouldn't run well enough to fly it.
Brought it back to my house, we fired it up with my field box and it ran perfect again ????

It turned out to be that his fuel was over a year old and that was the problem

He bought new fuel and it hasn't missed a lick since
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