MG Car Repair: Ignition Coil, ballast resistor, electronic ignition systems

Question
You helped me a short while ago with a problem with my head lights. All is working fine now. Traced it to a bad ground. Thanks!

I have another question about replacing my ignition coil. I picked up a LUCAS DLB105 Sport Coil on line, and wanted to make sure it would work with my 1977 MBG roadster. I'm using a standard lucas coil, with a resistor mounted to the car frame, and one wire going to the coil. Does this new coil also use the resistor? I've seen some part catalogs that say certain coils don't need the resistor. Please advise.Thank you.
Bob

Answer
Hi Bob,
The coil number does not do me any good to ID the coil. However, I can tell you how to ID a Lucas coil for  "Resistor" or "Non-Resistor" coil. (some times it is just written on the coil, either it will say "12 volts" (use without a resistor) or it will say "Use with Ballast resistor") If any coil says "6 to 8 volts" on it then uses a resistor.
A sure way that I use, is to check the ohms across the primary windings (two small connections) If it is 3 to 3.5 ohms it is a NON-Resistor coil. If it is about 1.5 ohms then you MUST use a resistor. (Note! most electronic ignition systems use a resistor and a resistor coil) (Don't forget to look at the (+) and (-) on the coil for connecting.)
Howard