Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Distributors & Ignition Systems: Operation
As the distributor shaft turns, a reluctor rotates inside a pick-up coil assembly. As the reluctor teeth pass the pick-up coil, a signal is generated similarly to that produced by a small magneto generator.
The signal is produced in exact synchronization with distributor shaft rotation, four times per rotation and at equally spaced intervals.
The signal generated is sent to the IC ignitor, which then switches current on or off in the ignition coil primary circuit. As current is shut off, the magnetic field in the coil primary collapses. This results in a voltage surge in the secondary, firing the spark plugs.
The centrifugal advance mechanism is located below the rotor assembly. As engine speed increases, the weights move outward, causing the reluctor to rotate ahead of the distributor shaft, advancing timing.
The vacuum advance has a spring-loaded diaphragm connected to the breaker assembly. As engine vacuum increases, the diaphragm pivots the movable breaker assembly in a direction opposite to shaft rotation. This too advances ignition timing.
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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