Only Firing on Two-Cylinders

All the fellows have great advice, but if this just all-of-a-sudden started, I would look for the simple things first. Cracked distributor cap, or mag cap (whichever your running) spark plug, like some of the guys said. Something dumb. You say it's a show tractor. Is the engine fresh? There's so many things that you have to take into consideration. If it's a freshly done resto and the engine is fresh, I would have to think it's something simple before I pushed the panic button. To me it sounds like it's an ignition problem. Something is causing the ignition system to go to ground and knock two cylinders out on ya. Run through the ignition system slowly. Check the coil (if equipped) for grounding to the high tension tower. You might be able to find the problem fast in the dark while the engine is running. Find an arch, or a spark, and there's yer' problem...
Good Luck! Hope you make that show!! Steve B.

You know I have a JD that for some reason will have a cylinder go dead on me, and what it has always turned out to be is a sparkplug that has gone bad on me. I would suggest doing a simple test of removing one of your good sparkplugs that you know is firing and putting it in one of the dead cylinders that is known to not be firing and see if you get fire in that cylinder, if so then get some new sparkplugs. I have had sparkplugs drop out dead on me on my truck too, and I hope I don't hurt anyones feelings on this but I refuse to put champion plugs in anything I own, I have found they seem to go bad faster than any plug I have ever used in my tractors or vehicles. Hope this helps ya Phil, I know how much it means to have the tractor looking good as well as running good.

Scott

Frist I would think Scott is on the right track and after, tring these things, I would start looking into a major job of enghine work. Sound like plugs use AC if you can. In my wd's that oil them up, I use AC they will last about 4 times as long as champion Plugs. Normal for them to go out slowly, but if you were running her very slow, she may have done it fast.

If you don't have new plugs sray with carb cleaner. Wire brush and spay with carb cleaner again. Take a knife and clean off the electrode ( that is the steel pin in the plug, sets under the arm or plug ground ) DON"T scrach the porclein ( glass ) spay one last time . Get sand paper or abrasive cloth and clean between electrode and the arm. Gap and sray with starter fiuld and let dry. You have got a plug with good chance that it will work for a short time.

Sand blasting is the best, all most like a new plug.

Next if it does not run right. Take all plugs out. Turn enghing over with your figure in the plug hole, becareful not to push too tight(don't get hurt), your see if the compression is there.

If that is ok, then look at your wires. Not a fun job. You may get super charged LOL, Dam hot shock. One at a time take off of the plugs and see if they spark. By the way some times you can get a plug to fire this way, hold about 3/8" -1/2" away from plug and they often fire.

Good Luck !!

Be Safe !!

Punchie