[solved]Trouble with a Tee Dee .049 with a new aluminum carb

**RknRusty** Thu Aug 23, 2012 5:25 pm

The last time this .049 flew back in June it ran fine, as it always has, but the carb was cracked when I cleaned it up after flying. So I put a new aluminum carb on it with the o-ring and Teflon washer. It's been hanging in the shop until today.

I was getting the fleet ready for this weekend, put on a new bladder and new tubing, a clean filter and a smaller 5" prop(rather than 5.5") and gave it a rip. With a half ounce of filtered fuel in the bladder it cranked up fine, running about 18.5-19k RPMs, not fast for a Tee Dee, but this one has never been a super screamer.

After a couple of minutes and half a tank it stumbled and stalled. I re-cranked it and had to keep fiddling with the needle to keep it running and it quit again before the tank was completely empty. I checked the head and glowplug, removed the third shim and filled it up with an ounce of fuel. After a half ounce it started slowing and I fiddled with the needle but lost it. I re-cranked it with the remaining fuel and it ran fine for a minute and started stumbling again. I was able to keep it going with slight needle adjustments. I never did figure out if it wanted to be richer or leaner, the adjustments are so minute. I'm thinking richer. When it was almost empty, maybe 5cc left, it cut off. There are no drips or signs of a leak when I fill it and just let it sit, and no air bubbles in the line. This is the same fuel the Norvel has been drinking with no problem.

I may fiddle with it later tonight. This is the first time a Tee Dee has failed to run perfectly for me. I haven't checked the backplate because it's mounted, but if y'all don't have any ideas I'll look at that next. If it still won't behave I have a plastic carb I can put on it.

Any ideas?

**Cribbs74** Thu Aug 23, 2012 5:35 pm

Sounds like some gunk came loose and partially jammed up the NV or venturi.

Ken Cook Thu Aug 23, 2012 5:40 pm

Rusty, I had this happen with my setup like yours. Is the driveplate binding against the front of the new aluminum body? I ended up lapping the aluminum body on a piece of glass with fine paper and oil. Some cases are just a few thousandths shorter. It was definitely causing drag. Another trick I use prior to starting. This needs to be done if you remove the needle and lost your setting. Pick the plane up, point the venturi to the ground. Open your shut off /clip that's preventing the fuel from coming out of the bladder. Watch the drips, they should be about 3/4" apart when dripping. Upright the plane and start. I pinch the line prior to launch to check to see if it leans up. If it wants to quit, back the needle out a touch and repinch. It's also a good practice to run for a few seconds and get some heat into it prior to setting. I'm assuming there's no varnish in the cylinder as well. The Davis Diesel devarnishing brushes work very well. Ken

**RknRusty** Thu Aug 23, 2012 7:08 pm

Ken Cook wrote: Rusty, I had this happen with my setup like yours. Is the driveplate binding against the front of the new aluminum body? I ended up lapping the aluminum body on a piece of glass with fine paper and oil. Some cases are just a few thousandths shorter. It was definitely causing drag. Another trick I use prior to starting. This needs to be done if you remove the needle and lost your setting. Pick the plane up, point the venturi to the ground. Open your shut off /clip that's preventing the fuel from coming out of the bladder. Watch the drips, they should be about 3/4" apart when dripping. Upright the plane and start. I pinch the line prior to launch to check to see if it leans up. If it wants to quit, back the needle out a touch and repinch. It's also a good practice to run for a few seconds and get some heat into it prior to setting. I'm assuming there's no varnish in the cylinder as well. The Davis Diesel devarnishing brushes work very well. Ken

I'll check the driveplate clearance. I wondered if something was binding with heat expansion. One thing I do know is the NVA is clear. I just the other day bored a new venturi, polished it and blasted ALL of the orifices with brake parts cleaner and then alcohol. I'm downright anal about clean and clear NVAs. In fact I flushed it again and switched bladders before my second try today. I know the needle setting, exactly 2.5 turns and it always cranks right up with no fiddling. I do let it get hot before setting it for launch. Today I was running flat out WFO. There could be varnish. I haven't opened it up and cleaned it since I got it in November. It probably has an hour of run time on it since then. But I do add an extra 3% drugstore castor to my fuel, so varnish is possible. It feels right when I cold flip it though.

Thanks for giving me something to think about, especially binding in the front end.

**RknRusty** Thu Aug 23, 2012 8:09 pm

My driveplate endplay is .013" cold, how does that sound?

**Cribbs74** Thu Aug 23, 2012 8:17 pm

You mentioned varnish. Did you check on that? My Babe Bee got all varnished up running in hot weather. It was real tight when hand rotating the prop by with the head off.

Ken Cook Thu Aug 23, 2012 8:23 pm

The fact that you do indeed have end play is good. I don't believe that .013" is out of the question. Your completely certain that the glow plug was indeed tight? I've had some real funny business with that and since replaced all my shims with new ones as they keep the head tight and don't loosen. Ken

**RknRusty** Thu Aug 23, 2012 9:15 pm

Yes the plug was tight. It's a 1702 Cox head with 2 shims. I put a plastic carb on it and now it runs 7 minutes without wavering at 19.2k and uses every drop of fuel. Three times in a row with identical results.

I'll put that aluminum carb on another engine sometime when I have time to mess with it. But for now the plane is ready for Saturday. I washed out the bladder with alcohol, hopefully it'll still be good Saturday. But I have 5 spares already made up and I have a good quick-change system.

Thanks for the assistance. It was either too little end play or a leak.

**RknRusty** Thu Aug 23, 2012 9:16 pm

cribbs74 wrote:You mentioned varnish. Did you check on that? My Babe Bee got all varnished up running in hot weather. It was real tight when hand rotating the prop by with the head off.

I think this engine needs some varnish. Smile

It doesn't have near as much compression as my .051.

Jason_WI Thu Aug 23, 2012 11:00 pm

I do not like the aluminum carb bodies. I have an early one before they added a teflon washer and o-ring. I can almost guarantee it leaks. I know it pains some here to buy from MECOA but the plastic carb bodies really are better and look better in my opinion.

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[solved]Trouble with a Tee Dee .049 with a new aluminum carb

[solved]Trouble with a Tee Dee .049 with a new aluminum carb

Re: [solved]Trouble with a Tee Dee .049 with a new aluminum carb

Re: [solved]Trouble with a Tee Dee .049 with a new aluminum carb

Re: [solved]Trouble with a Tee Dee .049 with a new aluminum carb

Re: [solved]Trouble with a Tee Dee .049 with a new aluminum carb

Re: [solved]Trouble with a Tee Dee .049 with a new aluminum carb

Re: [solved]Trouble with a Tee Dee .049 with a new aluminum carb

Re: [solved]Trouble with a Tee Dee .049 with a new aluminum carb

Re: [solved]Trouble with a Tee Dee .049 with a new aluminum carb

Re: [solved]Trouble with a Tee Dee .049 with a new aluminum carb

Re: [solved]Trouble with a Tee Dee .049 with a new aluminum carb