The condenser cushions that arc, making point life much longer. The high voltage now travels over to the distributor, where the rotor metes the high-voltage pulses out to the correct spark plug.Īll that current flowing across the points doesn't like to stop suddenly, and can initiate a small arc, which eventually erodes the tungsten contacts. This induces electrical current into the secondary windings of the coil, where the current is raised to 20,000 volts or more. When the points open a few degrees of crankshaft rotation later, the current is interrupted, causing the magnetic field to collapse. This current generates a magnetic field in the coil's iron core. As they close, current from the ignition switch flows through the contacts into the coil's primary windings and then off to ground. As the cam and distributor rotate, the points open and close constantly. There's a lobed cam on the distributor shaft that pushes on a small rubbing block on the movable side of the points. Then, the high-voltage electricity from the coil returns to the distributor, where the rotor inside parcels it out to the correct spark plug to ignite the fuel/air mix.
In the coil, essentially a transformer, it's stepped up to 10,000 to 20,000 volts.
The first uses a simple on/off switch, the ignition points, to provide properly timed pulses of 12-volt electricity to the ignition coil. The distributor on these older vehicles performs two related tasks. Nonetheless, there are still plenty of older vehicles, outdoor power equipment, boats and tractors that need periodic adjustment or replacement.
Yay! A generation ago, every teenager, every mechanic and a lot of vehicle owners understood the theory and practice of changing points and setting the timing. Modern engines use computer-controlled factory-preset self-adjusting ignition systems that never change their timing, have no moving parts and never need maintenance. Add in the indifferent, low-energy spark and incorrect ignition timing caused by worn-out points, and you've got an engine that won't fire-oh, and wet spark plugs too. Nothing like a high-compression V8 combined with a battery that hasn't seen a charge for a month and a half to make for slow cranking. It's a classic." That's harder to justify when your classic muscle car won't start.