I have a tower 46 that I'm trying to get tuned. I'm having trouble getting a good idle and a transition from idle to full. I've read through most evrything I could find here. When I turn the prop over by hand, I feel an immediate release in tension and feel a click when the piston is at the top. As soon as the piston begins it's descent in the cylinder, the force is present again. I removed the head and turned the prop by hand to see if the click was still present, and saw that the sleeve would come out about 1/32" - 1/64" when the piston came to the top. It would go back on the downstroke. I think this is the source of the click I feel when turning by hand. I can pull the sleeve up with my little finger with ease. Isn't the sleeve supposed to be tight against the cylinder wall?
Another question: I've read about shims but my instruction booklet makes no mention of them. They are called gaskets on the exploded diagram and are shown to fit under the cylinder head and the sleeve. They are also shown to fit between the crankshaft and the backplate. Two of these gaskets/shims were included with my engine. Should one of these shims/gaskets be placed under the cylinder head to hold the sleeve down or is this movement of the sleeve something that will cease when the engine wears more. Is this movement normal?

The sleeve is retained by the head. It doesn't move up and down when the head is bolted on.

The click you feel at TDC is normal for a ABC type engine. Don't worry about it. When the click is gone, -- your engine might be gone too?

The engine has aluminum shims or gaskets for under the head. I didn't use the extra ones.

The back plate has a O-ring to seal that area.

With the original tuned type muffler, the engine will tend to run a little rich in mid range. You can change to a different muffler (The OS 46 sizes fit) you will eliminate this rich mid range but the engine will not run as fast.

Enjoy.

Jim

Thanks Jim. Why do people use these shims?

There are times that you will need to ad one. There are a lot of new engines that come with extra gaskets.

If you like to run your engine all-out with high nitro fuel and a leaned mixture on a hot day, the engine will sometimes detonate. After you learn what it is, you can hear it when the engine is running pretty hard on the ground or when flying.

When a engine detonates it can cause a lot of damage to the engine. It will burn little pits in the piston on the exhast side or around the glow plug in the head. It will also break the element in your plug. Adding another gasket will calm this down for you.

Also you can blow one of these gaskets and then you have a spare.

Enjoy,

Jim

The fact that the engine is tight enough to alarm you when you feel the combined tolerances of the rod bearing and wrist pin fitting loading and unloading when you turn it by hand is also evidence that you still need to expect a little break-in time. I don't know how much experience you have, but be sure you tighten the head in stages and evenly. I have been surprised to see a lot of people start a head bolt and crank it dead-tight while the rest are completely loose. I like a #8 glow plug for transition troubled engines. Use a prop. that lets it turn around 14,500 after you richen about 500 rpm from peak. Don't let anyone convince you to lose confidence. I believe you will find you have a very nice engine.

Take care, Cliff

Zetor,

While what Cliff wrote may, or may not be true, a tapered bore engine, like the Tower is more than likely "gone south", if there is no longer any pinch at TDC, when the engine is cold.

If the pinch is gone, when at working temperature, the clearance is too large at TDC, for the engine to produce its best power. Overhaul is imminent.

Well 1 and a half gallons of fuel later, it will idle. Transition is a little better but is still lacking. If it takes 2 gallons of fuel to break in, then the value of this engine is no better than an os. 79.00+26.00=105.00. This doesn't include time, battery and starter usage. I should have just gotten the 46fx. My first engine was the 46fx and ran like a champ during and after break-in. I must admit that I believed all the complaints about these engines were coming from people too impatient to read the directions of the break in proceedure. I can tell you I read the directions tried the os#8, a3, and rc long glow plug. It was suggested in one of the first replies to this post that I put the 46fx muffler to smooth the transition but I no longer have that muffler. Will soldering a baffle in the tower muffler help me? I'm assuming that is the only real difference between the os muffler and the tower. Based on my experience thus far, I would consider buying another tower engine if it included, 2 gallons of fuel, 2 rolls of paper towels, and a full bottle of windex.

I had very good luck with mine AFTER a slight mishap.
Same problem you noted... rough idle, bad transition, and I couldn't shut the engine down with the throttle... all of the signs of an air leak.
The mishap was when I smacked the prop on the takeoff roll. It still sounded fine so I continued and flew. After a few minutes, I found that I had no throttle response... I was flying an Aircore Colt-40 on this power-monster at full throttle and had to do so until the engine died
Upon landing, I found that I had lost one of the prop tips, and the OOB situation had vibrated the barrel partially out of the carb, which became jammed against the stop screw.

Quick work with a file got the barrel working again, but at this point, I went through the carb-to-case joint and the backplate joint and sealed them with silicone sealer... I think I actually used aquarium adhesive (it's all I had 200 miles from home and 100 miles from the nearest hardware store).

I couldn't believe the difference. The engine tuned in wonderfully, shut down with the throttle, and never gave me a problem again.

I have a tower 46 that runs great, but I don't think i will get another one. I guess I was lucky, it only took 1 gallon of fuel. I still think the best bang for the buck is the tt pro 46. $75 and go wide open.