Any aftermarket coil manufacturer who makes claims about being able to provide extreme voltages at the spark plug is counting on having customers who don't understand what's going on in an ignition system. There is a huge difference in the theoretical maximum open circuit voltage that's available with a hotrod coil and one that flows less primary current and develops less magnetism around the secondary windings, but in the real world, firing voltage is determined by the condition of the spark plugs and the width of the gap. Once the gap is ionized and the spark begins to flow, it is IMPOSSIBLE for the coil to create any more voltage. If that happens at a clean, properly gapped plug with squared-off electrodes, it happens at less than 10K volts. Whether the coil is capable of 25K or 100K volts is a moot point. The higher secondary voltage coils do create a lot more load, and an increased probability of failure of the primary current control system, whether it's a set of points, or some exotic electronic pulse system dreamed up by P.T. Barnum and sold to gullible people who should know better. In the early 1950's, my father was modifying Lincoln Zepjyr 12 cylinder distributors to run on flathead V8 race cars, and ending up with a system that would jump a 3/4" gap with a hot blue spark- - - -and doing it with points, on 6 volts! He did so by manipulating the dwell time and allowing the coil to develop a stronger magnetic field before the points opened. A set of points only lasted a few races, but the hot spark was there when it was needed to ignite the alcohol/peroxide fuel mixture.
A standard 12 volt coil off the shelf at the local parts store will fire the plugs just as effectively as the same coil with a fancy paint job and a slick advertising campaign by Pertronix, no matter how it gets turned on and off. Does anybody really believe they make their own coils?
Jerry
