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Re: Re: Re: Ford 9N - coil replacement - simple procedure?
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Posted by Gerald on April 26, 1999 at 17:11:42:
In Reply to: Re: Re: Ford 9N - coil replacement - simple procedure? posted by me on April 26, 1999 at 15:29:40:
Nope, you have it all wrong. The ignition cycle begins when the points close and current flows in the primary. Because of the winding with a magnetic core the current rises relatively slowly storing magnetic energy in the core. When the points open the voltage across the primary rises to try to keep the current flowing. Current in a winding has a strong tendency to not change in amplitude. But the lack of current causes the magnetic field to collapse and create a great voltage. This is stepped up through the many turns on the secondary creating something on the order of 12,000 to 20,000 volts which makes the spark plug arc and ignite the fuel mixture. The capacitor absorbs some of the energy protecting the points. An engine will run without a capacitor, but not well and not long because without capacitor the points get damaged rapidly. In an engine with a distributor, the spark also has to jump from the tip of the rotor to the post on the distributor cap. Its the OPENING of the points that triggers ignition, not the closing. There are electronic capacitor discharge ignitions systems that charge a capacitor to about 300 volts and create the spark by discharging that capacitor through the primary of a coil, but they aren't common on 9N ford. Gerald
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