I have no idea what you are doing.If you are using a 12 volt battery to run your car, throw your 6 volt coil away.
Speedway sells coils with resisters set,or get a 12 volt coil and resister for a Ford 56 thur early 70s.
You can NOT use a 6 volt coil with 12 volts.
Why because a 6 volt coils needs about 3 amps and with a 1.5 ohm resister you will need 4 amps thur resister.They are made to handle 2 amps safely.Thats with putting 7 volts across coil and 6 across resister.