[FlatheadTed]

,Some good points above ,I don't think coils like running above 200 F ,( or Like Roter wrench says Coil deterioration .) have run a 6 v beige Yanky coil on my 34 for 25 years up by the generator recently I did a run down the freeway /motorway then got into crawling trafic by the time i got to drop of some brake shoes it was at 200 F and after wouldn't start I switched out the coil and bigo started ,Like AD 48 I shifted the coil to a cooler place ,I am montering how it goes but the Radiator is likely a contributor ,For JayChicago s question if you have a 6 volt battery and a 3.5 to 4 volt dropping resistor your left with ? if the points are open or closed that might have a berring on the test ,I don't know but think there are maybe other factors that come into it to ,I like a open to the atmosfear ballast resistor ,Cold air .