HELP! Coil problems with 6-volt H farmall

[Louie Bram]

I own a 1946 H farmall that has an original 6-volt system with a coil. For years the tractor has worked fine until one day I started it and two minutes later it died. I felt the coil, and it was hot, so I changed the coil when I realized it wasn't getting spark. two weeks later, that coil burnt out. I changed the points, plugs, condenser, cap and got another coil. Then that coil burnt out in a week. I thought maybe it was because of cheap chinese coils (the original one lasted 50 years) so I tried an IH coil. It burnt out. I can't figure out why I am burning out all these coils on the H. Does anyone have any ideas?
 

[JMOR]

[Jon Hagen]

On a 6V IH, not much to go wrong. Leaving the ignition turned on without starting the engine can overheat the coil, burning it up. Very high charging voltage can overheat the coil, check voltage at the battery posts with the engine running fast, it should not exceed a maximum of. 7.5 volts, 7.2 is normal..

A carbon or even metal core high voltage coil tower to dist cap wire that has burned back inside the insulation for a ways and causes the spark to jump too far, can cause the high voltage winding of the coil to short internally, wrecking the coil.
 

[Louie Bram]

I guess I think they are burnt up because a new one
seems to work fine for a week or so, then doesn't
work at all (at least until it gets to hot.
 

[Andy C]

You have a 6 volt battery in it, right?
 

[souNdguy]

i'm with jmor.. i find it hard to believe you are going thru 6v coils on a 6v machine with a 6v battery like shotgunn shells during dove season.

either the coil is staying powered.. or charge votlage is excessive, or you ar erunning some monster air gaps and making way too much high voltage potential needed for jumping..