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tower 46 troubles

Old 04-20-2005, 04:34 PM
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Craig F
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Default tower 46 troubles

I got this engine last year and had no problems, this year after about 20 flights it would die after full throttle
for a couple seconds.Tried new fuel , fuel lines, fuel tank , plug , adjusting the needle to the point of removing it
and it still does the same thing. So I took a carb off another 46 and this engine runs great, put the old carb on and
it dies at full throttle again. Took the carb apart and cleaned it with carb cleaner same thing. A friend suggested replacing the o-ring gasket when I reinstall the carb, been there done that. When I had the carb apart and sprayed cleaner all through
it I did notice it coming out where it should so fuel does pass through and it does run fine at idle, just not from half to full throttle.
I'm stumped so any ideas would be appriciated, thank you,,,,Craig
Old 04-20-2005, 04:47 PM
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zope_pope
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Default RE: tower 46 troubles

My Friend and I have had a similar prob with his TH .46 . We havent tried yet (we will this weekend), but we think that the muffler isn't pressurizing the fuel tank enough to get the fuel to the engine. We are going to try a different muffler and see what happens. You may want to try as well. The problem with his is we cant get the engine to run with a nose up attitude. Let me know if you figure it out because when we had it running, this thing screams!!
Old 04-20-2005, 05:18 PM
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Rcpilot
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Default RE: tower 46 troubles

You might try replacing the O-rings on the needles. They get worn and can cause air leaks eventually.

Also- the little clicker on the main needle can get worn and allow the needle to vibrate and turn in(leaner) or out(too rich) due to high RPM vibrations.

Are you running a filter on the pressure line between the muffler and the tank?
There is a lot of gunk in the muffler and stuff can flake off and eventually make it's way into the tank via the pressure line. Then it gets sucked up into the clunk and makes it's way to the needle. A tiny piece of carbon from the muffler can work it's way up to the carb eventually and make for intermittant running. It'll have you chasing your tail for hours. Then when you find it or figure out what it is-- it seams so simple. A tiny piece of gunk can reak havoc on the needles and carb.

I run filters in the pressure line and also in the supply line before the fuel hits the needle.

Also run a filter on your fuel jug. Filter the fuel BEFORE it goes into the tank on the plane.
Always fill the tank in the plane WITHOUT the filter on the clunk line. You don't want to risk pumping debris from your jug into your clunk filter. When you connect the line back up to the carb-- you've just introduced gunk from the fuel jug right into your carb. The line going to the carb should have a small 1" line and then a filter. That filter should NEVER be disconnected from the fuel line on the carb side. When fueling- you should disconnect the fuel line between the filter and the tank. Fill the tank and then reconnect to the filter.
Old 04-20-2005, 07:06 PM
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Default RE: tower 46 troubles

This is the same problem that the GMS47 engines suffer from and is indeed related to a lack of muffler pressure.

In our club we've solved it by fitting a different muffler (TT46 or Tower Hobbies) or fitting a restrictor to the outlet of the GMS muffler (and welding the two halves together because they always leak and end up falling apart anyway.

Whether the lack of muffler pressure is simply a symptom of bad tollerances in the carby is uncertain -- some have reported that drilling out the fuel-fittings on their engines have achieved the same result.

What we do know is that fitting a small restrictor is very simple, reversable and does the job just fine.
Old 04-20-2005, 07:36 PM
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Craig F
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Default RE: tower 46 troubles

Well thank you all for the replies BUT if you read the original post ,the problem is'nt in the fuel tank, I tried a new one,
it's not in the lines, I replaced them, the problem is in the carb because I put a different one on and the problem went away.
It also is not the needle valve, it has a remote needle that works fine with the other carb. See why I'm stumped!!
I guess I'll try taking the carb apart and cleaning it again, I didn't see anything the first time,
but my eyes are'nt what they used to be.. Craig
Old 04-20-2005, 07:39 PM
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w8ye
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Default RE: tower 46 troubles

Some of the Tower 46 carbs had a sloppy fitting barrel. The air would come in around the throttle lever end of the barrel.

There's been a very large thread going on here about the carb on the GMS 47. It's the same carb except the needle valve is on the carb.

http://www.rcuniverse.com/forum/GMS_...2290854/tm.htm

Read it.

Enjoy,

Jim
Old 04-20-2005, 07:47 PM
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laker500
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Default RE: tower 46 troubles

Craig,
I had a very similar problem to this with mine last year. My friends also was doing about the same. What was wrong with ours was believe it or not the low speed needle setting. I made the mistake when mine wasnt running right of turning the low speed in untill it bottomd out, then back 2 turns. This isnt even close to being right. If you have your manual for it yet check out the setting for the low speed. You have to go to WOT, then use a drill bit to set the space between the low speed needle and the spray bar. Its something like 7 or 8 turns out. If its in to far it actually goes into the spray bar and even at WOT there is no room for the fuel to come out. If you need the instructions I think I have my manual in my flight box. I could copy it and fax it to you. And your right, these engines scream like wild little banshees.
Old 04-20-2005, 07:54 PM
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w8ye
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Default RE: tower 46 troubles

High speed: 1-1/2 turns out
Low end: 2mm gap 2mm = about .08" <this is the gap he is talking about.

Enjoy,

Jim
Old 04-20-2005, 08:41 PM
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Craig F
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Default RE: tower 46 troubles

Well thank you all for your input regarding this "Brain Teaser!" and W8ye for the interesting reading. Witch
got me thinking..in my case anyway I know it's the carb because I tried another and the motor screams, that rules out the needle,
tank , plug and everything. The problem is fuel delivery in the other post people were altering the muffler to increase
pressure to the tank thereby pushing the fuel into the carb with more force and the engine ran ok. But what causes this need for more
pressure in the fuel delivery................LINT!!! yes thats right...belly button lint! ....well thats what it looks like anyway.
I took the nipple off the carb and looked in there but didn't see anything but thought there has to be something restricting the
flow. So I looked around and found a used staple, bent a tiny little hook on it, shoved it down the hole on the carb where the inlet nipple was, poked around and came up with fuzz, link, s#$t, what ever you want to call it. That explains it. The fuel can get
through ok at low speed, full throttle it goes lean cause the fuel is restricted. In takeing the carb off and shooting carb cleaner through
it went through the "lint filter" ok but the oilbased fuel could'nt. so all you guys that altered your tuned mufflers to increase the fuel
pressure ( and lost about 800rpm) time to get the lint out!!! I feel better....time for a beer or six....Craig
Old 04-20-2005, 09:23 PM
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w8ye
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Default RE: tower 46 troubles

Craig,

Glad you got where you were going....

enjoy,

Jim
Old 04-20-2005, 10:41 PM
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Rcpilot
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Default RE: tower 46 troubles

Glad you found the problem.

Are you running fuel filters? Most likely wouldn't be any "lint" in the carb if you were running a filter. A couple bucks in filters will save you all this headache again in the future.

I learned---the hard and frustrating way--that filters are cheap insurance against headaches--that are usually caused by beating your head against the tables and benches at the field when you got some kind of $h*t in your carb.

Just hate to see someone else suffer the same crud I went through.
Old 04-21-2005, 08:06 AM
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Craig F
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Default RE: tower 46 troubles

I plan to stop at the LHS on the way home from work today and pick up a few filters. I wish I had them a couple weeks ago
when this problem started I was about 20 feet up hanging on the prop on a Dazler when the motor quit and rekitted my
plane....Craig

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