My Tower engines smoke. Very little break in, fast and powerful. Large FP40 venturi, .283 diameter. FP needlevalve. Powermaster 5%, %22, (50/50 oil). Are you using all castor fuel, that might be your problem. I have run these engines using a stock muffler. But not for long. I use tongue mufflers that are free flowing, lots of holes. Also muffler pressure to a non-uniflow vent. Engine doesn't appear to be glow plug sensitive. Sometimes we use the hot Enya plug either a 6 or a 3 to calm down an FP. Forget which one. But I'll check. Frankly I abused the last two Tower 40 engines, setting them up, adding an extra head gasket. Very little break in, a tank on the ground at the most. Then ran them hard. Is there a lot of pinch? You may have an exceptionally tight one. Check the usual. Fuel leaks. O ring snug under the venturi. Needlevalve hole aligned with the venturi and tight. Back plate bolts tight, etc. The last Tower engine I used was literally put on a big foamy and run hard. It didn't quit. Not my most powerful Tower, but did top 12,100 turning a 10 1/2x4 1/2 apc. An extra head gasket will probably tone it down and give me a 2,2 break. I had mistakenly taken the engine apart a few times trying to locate a conrod or piston pin click. After checking everything and putting a nick in the piston, I tried another new Tower 40. THEY ALL CLICK. So. Onto the foamy sport plane to see if I damaged the innocent powerplant looking for problem that didn't exist. The engine worked.

Lee,
Do you really need the muffler?  Most of the recent break-in instructions suggest running without the muffler until the engine is broken in.
Steve

Steve: Nope I don't need the muffler just thought I'd use it to quite it down while running in.
Dennis: I have been running rich, I'll kick it up some more and let it run.

Dennis: The fuel is 50/50 on oil. I checked everything else seems fine. I'll try a different venturi the one in it is a tall white phenolic, I also have new NVA's but I'll re-clean this one just in case.  Thanks

The Tower is an ABC (or ABN??) engine which needs to have a pretty good rpm break in.  It has to get up to operating temps quickly, and run for about 2 min.  Let it cool and do it again, and again.  IIRC, it is recommended to run a slightly less prop load than you intend to fly it on to allow it to rev easier.  It soundn't be "screaming" but it needs to at least be on the edge of a wet 2 cycle. Nothing at all like breaking in a Fox 35.

I have seen an outstanding engine man take a new ($$) engine out of the box and fly it.  You got to be real good on the needle, but the "new" engines are much better for not taking as much break in before they will fly a plane.  They tend to keep getting better as you go.

I remember asking an 8 or so times NATS Champ what he did to a certain OS 40VF he was using.  he truthfully told me that he took it out of the box, boted it into the plane, hooked up the pipe and flew it.  It was box stock, "un run".

Still, run that Tower 40 on the ground for a while. 

Bill <><

sorry forgot to add the other part, break in with no muffler

Rereading the post leads me to think something's the matter, more than the choice of components. Is the needlevalve is defective. Stock FP40-20 needlevalves works well on our engines. Are you using a remote needle? Never encountered an issue like this. Dirt in the needle? Some kind of leak as mentioned earlier, tubing, venturi/case joint. Might simply try the large FP40 venturi plus FP needlevalve. All available from Tower. No.3 Enya plug should keep it lit. Extra head gasket or two. Backplate bolts snugged up, gasket intact? Was the engine ever taken apart. Is the cylinder liner alligned correctly?

Hey Leester!

All may be all right with your set up. After rereading you post again, I remembered that the engines heat up, might take fifteen seconds or so, at which point they hit around 11,900 rpm. The engines like to run around that speed. Let them run there. An extra head gasket or two should soften the upper end some and create a 2,2 break. It will not break like a classic engine but the break should be useful. Actually, I don't worry about the break too much. Concentrating on an even engine run, getting tank height right so it runs the same upright and inverted. Adjusting the pickup on a metal tank about 1/8" above the center of the venturi is usually close on a profile mount. Running these engines around 9000 is asking for trouble. They'll speed up until they hit a happy rpm. Adjust the needle so the engine hits the speed it likes. In my experience it will stick there making lots of power. At the field last weekend I happened to tack a Tower 40 that gives a consistent run on a huge foamy knock around plane. It tacked 12,100 with an apc 101/2x41/2. The engine stays lit and is predictable. Your engine seems to be consistent with the engines my club and I use. These are engines used in competition including advanced PAMPA. One of our engines on a P40 ARF took first at Brodak in Profile expert. Jack Weston's Gieseke Nobler uses this set up in advanced. Bob Gieseke said he liked the setup and wanted one like it. That was at the NATs a year ago. I am presently sand bagging it in beginner, will be out of there next season. Now that the stack of planks reaches above my knee. My Twister and Galaxy start in a second or two and give a consistent predictable run, flight after flight. You've broken your engine in enough, put it on a plane, let it rip. Adjust the engine so that flight rpm works for your pattern. Engines can be a tad overlean on the ground and mellow out in flight depending on vibration harmonics. Or it's possible for the reverse to be the case. When you hit a happy flight rpm keep the adjustment. A click or two either way may be needed when the humidity or temperature are high or low.

Been thinking about it and what kind of lap times at that RPM are you talking? I was going to put it in a roughly 40oz plane, I don't want to screw myself into the circle.