[Doug Money]

Will, your understanding is incorrect. The Model T coil needs 1.3 amps to fire if adjusted correctly. It is only possible to fire usefully once during the combustion cycle. Any further sparks would be way after TDC and not of any use to combustion. The same will happen in LDJs test, the modern coil will be so late so as not to have any use to combustion other than maybe a backfire through the muffler. Double sparking occurs when the coil fires before the 1.3 amp buildup is achieved and the coil is able to fire multiple times. This results in a less than satisfactory spark and subsequent sparks are wasted and a weak cylinder is felt. There is documentation available if you would like to read it that explains in great detail how it works. Let me know if you want to see it.