MG Car Repair: mgb ignition coil, ballast resistor, electronic ignition systems

Question
Hi Howard. I want to change the coil in my 1976 mgb. I am a little confused by my repair manual showing that a 6 volt coil was put in this car when new. Why did they use 12 volt coils up to 1974 then switch to 6 volts from 1975 on? I can guess it has something to do with the electronic ignition. I have a aftermarket crane 700 electronic ignition installed and was thinking of using a 12 volt(not 6 volt) coil with a ballast resistor. Do you think that is ok or should I look for a 6 volt coil? I am not sure what voltage coil is installed now but it does run hot to the touch. When the car is running, there is 7-8 volts on the coil + side through the resistor. Thanks, Mark

Answer
Hi Mark
All 6v coils must be used with a resistor wire (like installed on the car) or use a ballast resistor. 12v coils don't use resisters. Most electronic ignition systems require a 6v coil as did the late model MGB. 12v coils were used with a pointed distributor.
Howard