To answer your question about ballasts and such, there is a very good reason for running a 12V coil on 9V. When you crank the starter, it can draw 300-400 amps, which pull the battery voltage down, as low as 9 volts in a normal situation. Ignition coils are voltage multipliers, nothing else. To simplify my explaination, I'll use a multiplication of 20, which isn't really that far off on older systems. The coil multiplies 12 volts into 24,000 at the spark plug. When you crank the starter and the battery voltage drops to 9V, you're only getting 18,000V at the plug, of 75% of what you have when the engine is running. Actually it's more than that because if your charging system puts out 13.8V with the engine running, you're getting 27,600V at the plug. So when cranking the engine, you're only getting 65% of the voltage as you have with the engine running. So by designing the system so that you get the desired voltage at 9V, when you're cranking the engine and the ballast is bypassed, you get 9V to the primary side of the coil and the full spark. After the engine is running and the battery voltage is running through the ballast, you still have 9V and a full spark.
You can cause yourself some serious problem by bypassing the ballast on an electronic ignition system. Rather than use mechaincal points to close the circuit to the ground and collapse the magnetic field in the ignition coil (which causes a spark to be created), an TCI system (transistor controlled ignition) uses a large switching transistor to open or close the circuit to the ground. The Hall Effect sensor inside the distributor cap on our old Dodges creates a tiny electrical pulse each time the rotor passes by. This pulse is what turns the switching transistor on or off. The transistor body itself is conductive and must be insulated from any grounded surface. If not, the electricity is going to take the path of least resistance, through the ground.
Current flowing through any transistor creates heat and the more amperage going through it, the more heat produced. Transistors that flow large amounts of amperage can overheat and fail and are attached to a metal heat sink, which basically sucks the heat out of the transistor through conduction. To keep the transistor isolated from the ground, a thin piece of plastic is placed between the transistor and the heat sink.
Flowing higher than planned voltage through the transistor will cause it to run hotter than normal and the excess heat eventually breaks down the insulator, letting juice flow directly into the ground, bypassing the internal switching mechanism (very simplified, but I won't go into further details.) Instead of current "saturating" the ignition coil and then being sunted to the ground and forming a spark at the plug, current flows continually through the coil causing it to overheat.
I won't go into details of how I know, but take my word for it that not using a ballast resistor will fry the heat sink insulator in the ignition module and plastic cased ingition coils will get so hot that they split wide open and super heated goo runs out, then hardens into a solid blob. Needless to say, there ain't no sparking being done when that happens. In short, don't bypass the ballast UNLESS you're using a coil designed for points type ignitions that have 4-5 ohms of resistance at the primary winding. And if you do that, you'll lose the high voltage spark capability when starting.
