Ballast Resistor

Mr. Ray refers to people who have different views than him as 'morons'. He has been chased off a few forums because of his views & disinformation.
Disinformation such as using oil filled canister coils. Transformer oil has veeery poor heat shedding properties, one of the worst for liquids [ 0.13 v 1.00 for water ]. It's benefit is it's high dielectric strength. In contrast, epoxy dissipates heat 3-5 times faster TO.....which is probably one of the reasons it is used in modern coils. The cooler the coil runs, the lower the resistance of the windings & less looses.
A canister coil is the last coil you should use in your hot rod because of it's high leakage inductance & poor magnetic coupling. Both result in reduced spark energy. Transformer coils fitted to modern cars cost more to make than canister coils, so there must be a good reason why car makers spend the extra $$$........

The most informative info on ign I have found is on the website below by Dr. Holden. On the intro page, you will see at the start of the second line 'MDI ign v CDI ign'. Click on that, 73 pages. www.worldphaco.net