The tractor starts immediatly when cold. no choke. Runs very well. Fuel flow is good, no high spots in line. new points, plugs, has 12 v conv. Runs the implements very good for about 45 minutes, then starts to miss and eventually will backfire and quit. No way will it fire for 30-45 minutes. Then starts and runs well again for 45.

Cal, September 2008

Are you using a true 12v. coil? Most cars were using a "cold start" coil of around 6-8v. via a ballast resistor(Ford used a resistor wire, Vauxhall at one time used a small resistor mounted on the coil) to reduce battery voltage supplied to the coil when running. These coils should use a starter solenoid with an extra terminal to feed the coil when cranking the engine. This by-passes the resistor, ensuring the coil gets full voltage on cold starts - hence the name.
Using such a coil on 12v. will cause it to over heat and break down, which seems to fit your symptoms. Feel the coil to see if it is getting hot - carefully! Check the polarity is correct and try to read the voltage details. Some had it stamped on the cannister (if the label has gone)
Hope this may be of help.

Mr. Toad, September 2008

hi cal,you mentioned point's check gap also replace the condensor hope this helps

steray, September 2008