tea 20 woes... the drama continues...

Like JerryMT suggests, I suspect the coil is breaking down, but why? Given that the tractor (and coil) are 12V positive ground, the wiring to the coil is correct, the condensor, points, plugs, wires are all new, the ignition switch is not the culprit (bypassed it with no improvement), I'm dumbfounded. Bottom line, the coil has to be breaking down, but why/how.

Thanks to all those who try to help.

The other posibility is a bad key switch. These usually overheat in 10-15 minutes and the high resistance makes for a weak spark which causes the engine to die. Again it may start up again when in cools. Put a jumper acroos the key switch to eliminate or verify the possibilty that the key switch is bad.

Hope this helps.

Negative ground means, in simple terms, the negative terminal of your battery is conncted to the chasis, the chasis being the return loop for the current extracted from the positve terminal of the battery and connected to some load. The chasis completes the circuit. I hope I've made that clear. Your tractor, as I understand it, runns for awhile and dies. You have a 12 Volt system, YOU MUST HAVE A TRUE 12 V COIL or YOU MUST HAVE A RESISTOR TO LIMIT THE CURRENT TO A 6 V COIL OR YOU WILL OVERHEAT IT. Overheating will melt the insulation in the coil in about 20-30 minutes after starting and cause the engine to quit. In an hour or so the engine maybe restarted only to run for another 20-30 minutes and die. Certainly bad wiring will not help the situation but your symptoms, as described, can be caused by an improper coil. Make sur ethat you have a true 12V coil. The OEM system was 6V on this machine, I believe. ALs check the key switch because they can get crudded up and have a high reistance which will limit primary current and cause a very weak spark about 10 minutes after start up.

However, you say no spark?

If you have a multimeter or volt meter, when it dies do you still have 12 volts at the coil? (Between Neg coil connection and earth?)

You say you don't have spark - at the coil or at the plugs? Take the coil center lead out of the distributor cap, hold 1/4" from the engine and either flick the points or turn the engine over. No spark there?

Check you have the coil correctly connected. If still positive earth, the ignition switch is connected to the negative side of the coil; positive side of the coil to distributor points.

Next time it dies, connect a wire direct from the battery to the coil; if still positive earth, battery negative to coil negative. That will eliminate your ignition switch and wiring from your problem. If you still have no spark, one can only suspect the wrong coil or the coil or condenser is breaking down under heat or load.