To-35 wont start after warming up. 6v or 12v?

I have a To-35 that I have gotten to start again after professionally getting the gas tank cleaned, new fuel bowl, rebuilt carb, cleaned/new air oil cleaner, new coolant and getting ready to change the oil next. I replaced the battery which was 12v so I replaced it with the same v. battery. After about 15 minutes of idling the tractor will start to stumble and die even if I pull the choke it will die. I would have to wait a couple hours or the next day and it will run like new. This happened even before the rebuild..(i thought maybe the tank was causing it to die so that why i rebuilt it) The carb is getting enough fuel, I pulled the drain nut and it is running normally. My question is, how do I know if my tractor is a 6v or 12v? Im guessing the coil is getting to hot and its not working probably but how do I know for sure?

Also, if its the wrong battery should I change the coil and condenser and get a 6v battery? Or will just a new 6v battery help it not die after 15 minutes of running?

This is my great grandpas tractor that my dad used to drive daily.. Im hoping to get it fixed by Christmas for him.

Start it up and when it dies check to see how hot the coil is. If you spit on the coil and it steams off when you do the coil is going bad due to being a 6 volt coil but hooked to 12 volts. One needs a true 12 volt coil that say on it no external resister needed or you need a ballast resister in line of the ignition wire

(quoted from post at 22:07:46 12/15/21) I have a To-35 that I have gotten to start again after professionally getting the gas tank cleaned, new fuel bowl, rebuilt carb, cleaned/new air oil cleaner, new coolant and getting ready to change the oil next. I replaced the battery which was 12v so I replaced it with the same v. battery. After about 15 minutes of idling the tractor will start to stumble and die even if I pull the choke it will die. I would have to wait a couple hours or the next day and it will run like new. This happened even before the rebuild..(i thought maybe the tank was causing it to die so that why i rebuilt it) The carb is getting enough fuel, I pulled the drain nut and it is running normally. My question is, how do I know if my tractor is a 6v or 12v? Im guessing the coil is getting to hot and its not working probably but how do I know for sure?

Also, if its the wrong battery should I change the coil and condenser and get a 6v battery? Or will just a new 6v battery help it not die after 15 minutes of running?

This is my great grandpas tractor that my dad used to drive daily.. Im hoping to get it fixed by Christmas for him.

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Look for tags or numbers stamped into the starter, or generator (or does it have an alternator?). A web search of numbers you find may reveal if they are 6 or 12 volt.

Do you have it hooked up positive or negative ground? Is that the way it was hooked up with the old battery? The cable ends should have gone on easily. If one was loose and you had to expand the other one, you reversed the polarity.

Really need to determine why it is stalling. Catching it in the act is essential. Be ready to check the spark at the plug end of each plug wire at the moment it fails. Should get a 1/4 inch spark to ground cranking.

If good, check the fuel flow through the carb. Could be the cap is not vented, try loosening it regardless what it says. They can clog. Could also be vapor lock. Be sure the fuel line is away from the manifold. It should have a steel line, not copper.

As for the electrical system, need to determine if it was set up for 6v or 12v.

If it still has a generator, look at the tag, a black background tag is 6v, a red tag is 12v.

If it's been converted to an alternator, it will be 12v negative ground.

Have you checked to see if it is charging?

If the coil is still set up for 6v, running it on 12v will overheat the coil and burn up the points. (An overheated coil will be hot enough to burn your hand, normally it should be about the same temperature as the surrounding components.) It will either need a true 12v coil, or add a 1 1/2 ohm resistor in series with the primary lead from the ignition switch.

If when it dies, you determine it is loss of spark, check the voltage at the coil. Could be a failing ignition switch. Also check the distributor shaft for side play. It needs to be tight or the points will not stay set.

You asked about the condenser. It uses the same condenser for 6v or 12v, BUT!!! new condensers are known for being bad out of the box. If you have an old one, try it. They can do strange things!

After a year I noticed the fuel bowl is leaking slightly so I believe air is coming in with the fuel. My fix was keeping the tank full and it helps with keeping pressure on the carburetor to just allow fuel through. I have adjusted the fuel bowl slightly to help with this (fuel bowl still leaks alittle) tractor rens great but bogs some times when on a hill