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rotorwrench · 11-13-2021, 12:05 PM

The spark is a product of a high voltage step up from the reversal of the magnetic field in the coil. The secondary winding in the coil is connected to the primary very near only one of the two terminals of the primary coil so it doesn't have a complete circuit to it. The polarity of the COIL depends on which side of the primary is connected to the "power" from the battery.

Back in the day, they marked coil terminals with abbreviations for "switch" and "distributor" so that folks knew how to connect them. After the change from positive ground to negative ground they started marking then + or -. This is confusing to some when using a modern coil in an old positive ground system. To further confuse things, some coil manufacturers get the markings wrong. Polarity of the coil depends on them being connected correctly to get the best spark from the other end of the secondary coil.

It takes high voltage to ionize the air enough for a spark to jump. A lot of that spark is voltage and very little is amperage or whatever you want to call it.

Electricity is a lot easier to explain if a person sticks with the conventional way of describing it.

11-13-2021, 12:05 PM	#20
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,436	Re: Positive Ground The spark is a product of a high voltage step up from the reversal of the magnetic field in the coil. The secondary winding in the coil is connected to the primary very near only one of the two terminals of the primary coil so it doesn't have a complete circuit to it. The polarity of the COIL depends on which side of the primary is connected to the "power" from the battery. Back in the day, they marked coil terminals with abbreviations for "switch" and "distributor" so that folks knew how to connect them. After the change from positive ground to negative ground they started marking then + or -. This is confusing to some when using a modern coil in an old positive ground system. To further confuse things, some coil manufacturers get the markings wrong. Polarity of the coil depends on them being connected correctly to get the best spark from the other end of the secondary coil. It takes high voltage to ionize the air enough for a spark to jump. A lot of that spark is voltage and very little is amperage or whatever you want to call it. Electricity is a lot easier to explain if a person sticks with the conventional way of describing it.