Engin sputters.

We had rain here in the Mid-South the end of the week but yesterday it cleared off and you could not ask for a better day to fly. The only problem was the park that we fly at was a marsh pit. But we put on the boots and waded in.
We got the flight streak up and the way it looked to me it flew like it was on rails. Thanks to everyone that helped me get the CG in the right place. The old McCoy had not been attached to a plane in over 27 years and it went with hesitation. Thanks Guys. My son posted on Flight Lines… see Prop buster’s post for his story.
We did try fly our .049’s and here is my question.
I have two engines, a BW and a GB Cox. It seemed like I had lost compression on the GB and I found an old piston that fit just fine. The engine will start but after launch the engine will burp and sputter and will not make a complete run before it sputters and acts like it is out of fuel. The BW will make a complete run but it sputters a little. Today I ran both engines. The BW ran just fine. I still have the engines mounted on the planes and I point the plane up and down like the moves it would make if it were flying. The BW ran OK, go figure. The GB ran like it did yesterday. After starting I adjusted the needle to get it running at top speed. Then started to move the plane up and down like it was doing climbs and dives. It sputtered and almost quit. I fiddled with the NV and it perked up again. Started to move the plane around and same thing. I did that until it ran out of fuel. I am using Wildcat fuel, 18% oil, 25% Nitro. Could the fuel be the problem?
Let me know if more info is needed.

Thanks
Paul

Paul it probably is not the fuel as the Black Widow did ok. Next time you fly the Golden Bee point it up and adjust the needle 'til it peaks then allow it to run a little richer when plane is level. See if it then unloads after launch. If that dosn't do the trick disasemble the engine and check for crap in the fuel lines or NV.

I read you boy's post on flight lines, bet he is still excited.

First, the Golden Bee got a new/used piston...same cylinder, or was it a matched set? If you put a different piston (only), it will not be a perfect fit, so you'd need to do a bit of break-in.

Second, the Wildcat's 18% oil is all synthetic. I'd add 12oz castor/gallon to bring that up to 25% oil, just to get a decent amount of castor in the mix. Better for iron/steel/plain bearing engines, better for break-in...still not the right fuel for that McCoy. I'd run 5% or 10% Nitro x 25% Castor in the McCoy, with a good hot glowplug, and 9-4 prop.

Third, meticulous "fuel handling" will go a long way toward keeping your engines running right. Dirt and H2O in the fuel need to be avoided. Those 1/2a's have no fuel filtering except as you fill the tank, so I hope you're already doing that. Steve

Thanks Guys,
It was just a piston change on the GB. I will try to adjust it with the nose up next run. And run a few tanks thru for break in.
I do not use the Wildcat for the McCoy. McCoy ran great on the Fox Super Fuel.

Paul

What McCoy?

"We got the flight streak up and the way it looked to me it flew like it was on rails. Thanks to everyone that helped me get the CG in the right place. The old McCoy had not been attached to a plane in over 27 years and it went with hesitation. Thanks Guys. My son posted on Flight Lines… see Prop buster’s post for his story."

Pop on over and give him some feed back on Flight lines.

Thanks
Paul

An easy way to check compression on your GB is turn the piston to TDC and listen and feel if it hold the compression for a few second. If it get soft the instant hold it there, it may be too worn.

If you engine is prematurely stoping in the air, you are running too lean. Back off the needle a bit before you launch it.
Sometimes, you make be over compressed, especially if it can't hold a steady needle setting. Try adding another gasket, it couldn't hurt.

What prop are you using on the GB.

> Try adding another gasket, it couldn't hurt.
>
>What prop are you using on the GB.

Not sure is has a gasket. And I am using a 6-4 prop.

Thanks
Paul

OK, do you have a rod setting tool? These are cheap. If the piston/cylinder fit is too loose, take the piston out and set the piston on a flat surface without putting it inside the "container" and rap the ball to reset the rod. Check the fit. If it is still too loose, rap it a bit more. The piston will expand when you do this. You may end up having to lap it in back wards, but you can restore the fit this way.

Leonard,

Do you know of a source for a rod resetting tool? I built a Mouse racer so I can fly after, uh, .... I have to put the stunter (pieces) back in the truck. I've been running old engines with mix 'n match parts; TD cylinder and piston on a Black Widow, etc. I would have more flyable engines if I could reset a few rods....

I tried Competition Models. No luck there. Any suggestions?

Dave

Try Davis Diesel Development. Also Tee-Dee starter springs and high-zoot crankshafts for reed valve Coxes.

>Leonard,
>
>Do you know of a source for a rod resetting tool? I built a
>Mouse racer so I can fly after, uh, .... I have to put the
>stunter (pieces) back in the truck. I've been running old
>engines with mix 'n match parts; TD cylinder and piston on a
>Black Widow, etc. I would have more flyable engines if I
>could reset a few rods....
>
>I tried Competition Models. No luck there. Any suggestions?
>
>Dave

>Leonard,
>
>Do you know of a source for a rod resetting tool? (snip)
>
>I tried Competition Models. No luck there. Any suggestions?
>
>Dave

We have two different ones, but I don't remember the source of either. I am thinking one was either Carl Goldberg or even DuBro. One came with the little contraption that you set the piston in to keep it from expanding and the other you just set the piston on a wooden block and tap lightly.

Way too much prop. Try a 5 X 3 to 5.5 X 3.

Paul:

All the other advice is good but there is on other very simply quirk to the cox engines with built in tanks: the four tank attaching bolts tend to loosen up a bit periodically, making them erratic and hard to set. They don't need to be "falling out loose" to make poor engine runs. I have a Golden Bee and an RR-1 (if you're old enough to remember those, welcome to the "no hair left" club) which both need to be snugged up every dozen flights or so. While this problem is a plague on the .o2o Pee Wee, it also occurs on the other attached tank jobs.

Some of the modern bolt adhesives might end the problem, but be very careful not to make worse problems.

Also, be sure that the tip of a needle valve is not broken off in the
orfice ring. This happens from overtightening. Compare the needle with a new one or remove it and blow/flush to make sure nothing is in there. They will run this way but not take a consistant setting.

Hope this helps.

Paul,
If all the other stuff fails, check the seal inside between the backplate and the tank. If this has a small leak it could add fuel to the needle adjustment when you start and add air when fuel drops below the seal. It's a longshot.

Good point, George. It only dawned on me recently that there should be a tiny "O"-ring between the back plate and the tank tube. Replacing it solved a similar problem on one of our BWs.