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The conventional ignition system is relatively simple.
It consists of two systems: Low voltage input and high-tension output. When the ignition switch is turned to the start and run positions, battery voltage is supplied to the positive side of the induction coil. The low voltage flows through the primary windings in the coil to the distributor. Under the distributor cap is a rotor, a set of mechanical flyweights, a condenser, set of points, and a vacuum bowl pull rod (vacuum advance). The distributor shaft has an eccentric with eight high points. Low voltage flows through the points to ground. The points, which ride on the distributor shaft, open as they peak on the high points. The condenser is used to keep the points from arching upon opening.
This prevents premature burning of the points. The opening of the points causes an open circuit, causing voltage to search for a new ground. This collapses the magnetic field inside the coil, inducing voltage into the secondary windings of the induction coil. The secondary windings increase the voltage. That high-tension voltage (30,000volts) now looking for a ground, enters the center distributor cap tower via a high-tension wire.
From there it flows through the rotor, to the cap tower of the cylinder that's at its compression stroke. High-tension voltage flows to the spark plug via a high-tension wire. When the high-tension voltage reaches the spark plug, it jumps the gap in the plug to ground. This spark ignites the fuel-air mixture. As engine RPM increases, the mechanical flyweights and vacuum advance, adjust the exact degree in which the points open. Engine vacuum is used to operate the advance pull rod.