I bought a tower hobbies pro 46 engine new from tower. It ran good for the 1st 6 flights very strong and reliable. Then it deadsticked on one flight. Since the deadstick it will not tune up right at all. It will idle all day long but when i advance the throttle to full it surges from loading up real bad to leaning out and back to loading up. it will not run wide open. At wide open it does this and then trys to die. if i drop the throttle a tad above idle it will not die. When I give it full power it will come close to wide open then it drops rpms. It makes alot of nose in the carb like a cold leaf blower engine. The loud baaaa noise. I have turned the high speed needle to all kinds of settings from very rich to very lean and it doesnt change. i turned the low end from super rich to lean and it acts the same way. I even sealed the back plate and the carb joint with RVT.

WHat do i need to do to get it running right?

On what kind of airplane do you have your Tower Hobbies .46 engine? It sounds like you may be getting some fuel foaming. This is when the fuel in the tank is agitated by the engine's vibration, which leans the mixture. With some aiframes, the leaned mixture smooths out the vibrations, the air goes out of the fuel and the mixture richens. The engine slows down and the vibrations start again. You get a cycle of RPM changes.

Sometimes the engine goes lean enough that it overheats and quits.

You may also have the needles of the carb not in balance. Start out with a very rich idle mixture. Get the engine running and set the high-speed needle at full throttle. Then retard the engine and get the idle mixture set. Open and close the throttle several times. You would adjust the acceleration with the idle mixture. If you have to lean the idle to cure a rich acceleration, you may want to increase the idle RPM a hair to compensate.

Many times, people get a very, very low idle, but have handling problems. A bit higher idle can relieve a lot of difficulties.

If you still have the problems with the engine on the model, try it on a good, solid test fixture. If you still have problems, the engine h as a problem. If they go away, it's something in the airframe/engine/fuel system combination.

How did the breaking in of the engine go ?
What kind of fuel are you using ?
I know its cold in Albany [:@] ,some engines are hard to tune in cold weather.
Did you crash when it died and you dead sticked ?

the questions I'm asking will only help me and others diagnose your problem.

Good Luck

I am in south Georgia not really cold here

Well i didn't break it in. I did my TT pro 46 the same way and it ran fine on the same plane until the engine failed. The TH 46 ran perfect on this plane using 10% omega. When it dead sticked it surged like its doing now and died. i have a macs tuned pipe on it and a 9x8 mas prop. She really screams when she runs wide open. i peak the needle and drop the rpms a bit on the rich side with a nice smoke trail. Thats how i had it set and it was happy. I tuned on it again and still nothing.

One thing it does is idle very very well. When it idling i can advance the throttle wide open and it Will rev up to full rpm and the it slows down making the loud baaa noise from the carb. i also noticed today that it was actually spitting fuel out of the carb when it was loosing its power. if i drop the throttle back to near idle it and then advance it right away it will instantly sag, but if i want a few mins and let it idle and then nail the throttle it will run wide open for a few seconds and sag while spitting fuel from the carb. I changed the glow plug also and it does the same thing. When adaving the throttle slowly the sagging seems to start about 1/2 throttle. if i stop advancing the throttle and back off a tad to keep it running i can sometimes get to full rpm but its on the very rich side. While holding full throttle i can peak the needle and it will seem fine, but once i bring the engine back to idle and advance throttle it starts the sagging crap again. I pulled the lines of the engine and blew into the pressure line and fuel flows freely. i also blew through the needle valve into the carb and it wasn't stopped up. What it seems like its doing is getting flooded with fuel during the midrange rpm. Thats when it starts spitting a mist of fuel out of the carb.

I have always been able to get a engine running good but this one is different. i have never seen a engine do this before. I tried putting my TT 46 carb on the TH engine but its slightly large in diameter so it doesn't fit.

its really amazing how it ran so good and now its just a dog. compression is real good also.

What kind of plug are you using? Brand?


Enjoy,

Jim

I am not an engine expert, But if I were you I would go back and do the break in instructions on the engine.
Brand new cars have to go through break in periods beleive it or not so this little engine will also need it, although I hate breaking in a engine ,(only did it once so far) it helps alot. The purpose of the break in period is to help the engines cylinder to mate with the piston, before excessive heating and swelling do to heating occurs.

The cutting off when you rev. it up is due to the needle being set to rich. Its hard to get the smoke to disappear but in the long run it will be worth it......

Good Luck.

Oh yea all I saw was Albany so I assumed NY

Os #8 plug. I guess the orginal plug was a tower plug. it came with the engine. Any idea why this thing is drowing it self in the midrange?