[Shop-talk] Ignition Coils

[Bob Nogueira]

I need a   Lucas coil for my British built Isetta.   Looking through all the
Lucas coils I have in a box I see that each one seems to have a different
number. Looking on line the number of  Lucas coils seems to go on for ever.
Now  I know that there are coils that use a  external resistor and some that
that donbt .  I also know that there are 6 volt and 12 volt coils.  My
question is why are there so many different coil models?   I mean even
accounting for  screw in terminal and  Spade vs threaded posts  it seems that
there are far more  than the possible combinations.   What other factors come
into play in choosing the right coil?

Thanks for any input

Bob