[Mike K]

hi Stewart

It sounds like you have the divers bell distributor , a cap on each end of the housing .......

Ford re designed the ignition system and the crab style dissy fitted from 42 onwards was better setup .

The British type system was different again . I am not sure what type you have

The big problem with the 4.5 volt system is , the standard dropping resistor cannot cope with the wattage . eg

The voltage regulator is putting out 7.1 to 7.4 volts , which means the resistor has to drop almost 3 volts at whatever amps , result is , the resistor gets hot , its resistance value rises , causing it to become in effect , a current limiter . The result is .....You lose spark . The resistor is usually a wire wound type on a ceramic former .

If your coil has been run without a resistor , it may be cooked .

To test your coil , use a multimeter on the low OHMS range , on the squat coil that fits on the divers bell dissy , there is a pigs tail grounding coil of wire underneath . This is from memory , put the leads between the terminal on top and the pigs tail and you should see a few OHMS , around 4 I think .

You use OHMS law to work out simple electrical stuff :

Current = Voltage divided by resistance .
voltage = current X resistance
resistance = Voltage divided by current

I suggest that you make up a dropping resistor that can handle the wattage , or maybe mount the standard resistor on a heat sink to keep it cool . eg. a lump of metal with fins on it , these are used in electronics to keep transistors cool , easy to buy .

Mike