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post #1 of (permalink) Old 07-10-2001, 07:41 AM
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What does an ignition module do?

I've always wondered what the function of an ignition module is. I know it's a $12 part that can make your engine totally nonfunctional, but what exactly does it do?

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post #2 of (permalink) Old 07-10-2001, 09:16 AM
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Re: What does an ignition module do?

The type of ignition module your talking about (just 4 pins) has the basic of function of setting the dwell. The old point ignition system had a mechanical dwell setting to set the amount of time (which was measured degrees) the spark plug was sparking. The ignition module has a saturation time that sets the dwell of the spark plug sparking. The saturation time is the about of time the ignition coil is discharged. The saturation time is measured in milli-seconds ( 1 / 1000 of a second is a milli-second). A typical point system discharged the ignition coil in about 300 milli-seconds. The typical HEI ignition module discharged the ignition coil in about 450 milli-seconds.

Once the module becomes non-functional, there is no spark because the coil is not discharged of its high voltage through the spark plug wire and spark plug.

The Corvette ignition module of the late 70's has a longer saturation time than the standard ignition module. Many aftermarket performance ignition modules are really just copies of the Corvette ignition module. There is a small performance gain with a Corvette ignition module.

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post #3 of (permalink) Old 07-10-2001, 11:07 AM
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Re: What does an ignition module do?

It basically magnifies the signal of the pick-up coil.
Dwell with points is the time measured in degrees, like dave said, the points are closed. The satuation time that dave mentioned. The longer this time, the more energy the coil can build. The higher the engine speed the less time the coil has to build this energy. Back with points, a condenser was used to store extra energy. A coil fires when the primary current flow is disrupted. Electricity don't like to stop once flowing. So disrupt the flow by breaking the circuit with points or module the primary current looks for a new place to go. The secondary windings in the coil. These are of finer windings and many more windings then the primary windings. This amplifies the current enough to fire the plug. The secondary windings are wrapped around by the primary windings in the coil. Someone smarter then I will have to explain exactly how the current is transfered.

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