weathervane

Hello everyone, I have an older K&B .61 (square carb) that I can not get running. It has not been run in about 13 years. It is mounted inverted on a Cub that I'm reworking. I installed a new fuel tank with new fuel lines. I put a new glow plug in also. (OS #8) It's all I have at the moment. At first it would not suck fuel to the carb. I adjusted the high speed needle about a turn, and got fuel going to the carb. It will not allow fuel to the cylinder. I pulled the glow plug and it was as dry as a bone. I'm not getting fuel through the carb. Can my needle settings be causing this? What is a good starting point with the needles?

Thanks, Andrew

rcdude7

My Feedback: (264)

A used engine that has been idle for 13 years usually needs a good cleaning inside before it will run properly. I have bought specimens like this on *bay that are gummed up to the point they won't even turn over. The fuel pasages inside the carb are tiny and the smallest amount of crud will cause problems. Remove the engine backplate and dis-assemble the carb. Use some alcohol (works better than any other solvent) and a small brush to loosen the old oil and castor. Look at the bearings to ensure they are not badly rusted. If they are, replace them now. Oil the parts and re-assemble them.

MrMotor

Try turning the plane over and trying to start the engine if you are getting fuel in the carb. You could also have a stuck ring from sitting so long.

DarZeelon

Andrew,


If your fuel is not very old (i.e. still has enough methanol in it and has not absorbed too much moisture - methanol is hygdoscopic...), the plug gives a good orange glow and the engine has a decent compression, this engine must at least manage a brief 'growl' if all three are present in the combustion chamber...
Turn the plane over so the cylinder will be upright and check the carburettor for fuel flow, by connecting a length of silicone fuel-line to the carburettor and blowing through it, while operating the throttle and/or turning the main needle.

Now, reconnect the line from the fuel tank, make sure the main needle is ~2.5 turns open, open the throttle to full, choke the exhaust outlet and flip the prop over twice...
You should see fuel in the line and even in the carburettor.

(*) Set the throttle to 20% open, make sure the engine turns over and now, power the glow-plug and flip the prop, or 'blip' it with the starter.

If the engine still maintains the 'no comment' stature, carefully remove the glow-plug and drip 3-4 drops of fuel directly through the plug hole, into the chamber.

Reinstall the glow-plug and repeat the (*) paragraph. It should respond.


The presence of good fuel, compression and an ignition source, are all necessary for combustion to occur.
Adjusting the engine is the subsequent chore and this is what the high and low-speed needles are there for.

Sport_Pilot

Dar is correct. But so is soaking the engine in fuel or alcohol. The old engines get gumed up pretty bad with old oil.

weathervane

Thanks for the info guys. I will put it on a test stand and soak the carb in alcohol. Between turning it upright and the good soaking I'm hoping to get it working.

Thanks again for the help.
Andrew

weathervane

I got it running guys. A good soaking and a cleaning does wounders.
Thanks again,
Andrew