rsieminski

I broke it in per the instructions for 20 oz of fuel. At this point it seemed to hold wot, a bit rich, but held rpm. Adjusted the idle screw, ok, 2300 rpm. When you try to go from idle to wot, it chokes and dies! Even slowly, it just dies. Leaned the needle, richened the needle, added two shims,... Short of a hammer, what can I do?
Thanks,
--Rick

PeterH

There's elements to the equation we don't know just yet. Did you try this throttling test with the muffler installed? If not, you're just about guaranteed to have the results you got. Assuming you do have the muffler installed, have you tried changing to a hotter glow plug, like a Fox Miracle Plug or OS #8?
Plug heat range can dramatically influence throttle response. You mentioned running 20 ounces of fuel through the engine. More indicative of how much breakin got done, how many cold starts were involved? Breaking works while the engine is heating up, not when it is running in a steady state. For example, 10 runs of 2 minutes each with a cooldown to stone-cold between runs will break in an engine more than two runs of ten ounces each.

rsieminski

Yes, the muffler was installed. I checked the tank lines -- ok, I have tried a #3, and #8. The 20 oz was prob. 5 cold starts. I did it per the instructions.... run wot rich, quick pinch, 30 sec, quick pinch,... lean a little, quick pinch, 30 sec, ...

fotta

Mine took a long time to break in. I used a hotter glow plug (McCoy 59 or was it a 57 ?) and eventually it would transition quite well, most of the time.

Still, I sometimes had problems with it stalling in mid-air at the worst times, wehn transitioning from low to high revs. It got better with time but I never really trusted it.

Conversly, It never wanted to quit when the throttle was shut off to Zero, probably due to an air leak somewhere. I tried sealing everything I could think of, to no avail.

I guess you get what you pay for. On the plus side, it had lots of power when it was running well.

I think that if you take your time and break it in thoroughly and pay a lot of attention to setting the needles, it'll be okay.

BTW, Tower's customer service is very good.

Not meaning to slam the Tower engines, but my experience has made me a believer in OS engines...

Jazzy

Rick,
Could be running too rich.
Could be too lean at idle and too rich at full.
Could be too rich at idle and OK at full.
Could be an air leak.
Could be the fuel.
Could be that it needs significantly more break-in time.

Trying to properly adjust the needles of an engine that is not broken-in enough will often have the characteristics you mentioned. Run it on the ground or test stand for 4 or 5 more tank-fulls and put a piece of fuel tubing over the needle. In my opinion those needle valve O-rings cannot be trusted for very long. After running the poop out of it set the main needle just slightly rich, (normal running setting), and slowly bring down the throttle. If it starts slobbering and heavy 2 or light 4 stroking lean the idle needle a little bit at a time until you can get the throttle down to a respectable idle. Conversely, if it starts to lean out, richen the idle needle and proceed. It can be time consuming but generally works for 'finicky' engines.

Some engines can be mounted on a plane and flown right out of the box. Some require a long break-in time-even more so than the manufacturer says.

Good luck,
Jeff

ShempHoward

My Feedback: (3)

Given the reputation of this engine since it came out my vote is for an "air leak" probably either in or around the carb or possibly in the back plate. These engines do have a bit of a well deserved reputation for problems but IF and WHEN the problems are sorted out they seem to run well.

rsieminski

Yes, mine has the air leak, and will not shut off with the throttle fully closed. I kinda look at it as a benifit, it now will idle at ~ 1800 rpm. I ran another tank through it at a rich setting, every 30 sec. or so giving the line a quick pinch. I would run it for ~ 3 min, then shut it down and let it cool, then do it again. It goes from idle to wot better, although it seems to need to be hot first. You have to kinda juice it progressively further and further, then it'll do it without hessitation. Will this get better? Is this a plug issue? Or maybe a nitro issue? I have an A3 in it now w/20% nitro, 21% oil fuel.
Thanks,Rick

Jazzy

Wow. That is a lot of Nitro. Rather expensive I'd imagine...
When first starting an ABC type engine it is important to let it warm up-quickly. I have found that upon starting letting it run at anywhere between half and full throttle for 10-20 seconds gets the goobers out and achieves a good piston/sleeve fit. Once they reach operating temp most generally run great (if properly tuned).
Since I don't buy O.S. plugs (except for the type F) I believe the A3 should be fine. I've had great success with the K&B 1L.
Run it some more and try to find the air leak. It should get better.

rsieminski

The LHS sells everything for 14.99. I really wanted 15% this time and the last, but this time all they had was 30%. I thought the engine might be running a little hot, but no way for me to tell. I still have the 2 extra shims in it. It's now eaten up >1/2 gal of fuel and it hasn't seen any airtime yet. It does seem powerful though. I thought I might have had too little prop on it, so now I have an apc 12x4 on the nose, and it spins it at 14K.

Oh yeah, forgot. It seems to get rich if it idles for a min or two. Is this typical?

Eohlin

My Feedback: (5)

My dad picked up two of these motors and several others have them at our field...they are great running motors.

However, we had the sames problems with getting it to run right and getting it broke-in.

Here's what we did... 5% Fuel.

The engine ran great, excellent transition and would run tank after tank without issue.

Give it a try...the guys from Morris told me any motor with high compression will run better with less nitro. This was also the trick to make the MDS engines run.

Good luck and let me know if it works.

Eric

cbk07

My Feedback: (64)

First of all, do you have an exhaust deflector on the muffler? A guy at our field had a terrible time with one of these engines until he removed the aftermarket deflector he had installed. Turns out it adds too much backpressure or something. He also found that by adding the supplied head shim made it easier to tune. Slightly less R's but much more friendly motor in the end. Hope this helps, cbk

sport10

I have had one of these engine for quite some time now. The only problem I had was the engine not wanting to shut down. This problem eventually went away and the engine runs excellent now. I am not using the supplied shim and always use 15% nitro fuel and a Tower power plug. Do not use a idle bar plug in this engine it seems to messup the transistion of the engine. Other wise a great running and powerful engine.

rsieminski

sport10,
You have no shims or gasket under the head? Does it leak? With higher nitro, use less compression, ... uh... right? Maybe the other way around? I put all 3 in because I didn't know what to do.

davham

My Feedback: (4)

One word--EBAY--

I had one and it wouldn't shut down, had to hold my thumb over the carb. My also tended to lean out in the air. I would transition and run great on the ground. Never could figure it out, eventually sold it.....Dave

Herb-RCU

I bought a GMS .47 last fall and had the same problems. I believe they are the same engine. If they aren't the thought still applies. Anyway, I couldn't get it to run right after hours of tinkering. I finally sent the thing to GMS. It turns out that they had put a needle valve for a .32 or something in the carb instead of the correct one. I got it back, spent about a minute tuning it. I couldn't be happier with the engine.

BTW, mine also had problems shutting down. I put a little bit of silicone on the o-ring at the base of the carb and replaced it. Solved the problem.

Good luck,

Herb

Alastair

I had a Tower .46 in a Stick and it ran with a lot of power and had good transition. I also had the air leak preventing it from shutting down. It did have to be tuned everyday to have it running reliably, unlike an OS .46 which you can leave and it justs runs great all the time. When running well though I would trust it to fly in at idle, make a slow pass, pull vertical and give it full throttle right in front of a lake and it never gave me any problems (This was using a 10 x 7 prop). One day it just stopped running well and no matter what was done it ran poorly. The engine was sent to Hobby services for repair and was lost by them. $75 was then credited to the Tower Hobbies account. I have not used another one since.