Here's why you need more than just a light and the proper procedure:
1. Timing Light: The timing light is crucial for *seeing* the crankshaft position at a specific engine speed. It shines a light that flashes in sync with the engine's ignition pulses, allowing you to see where the timing mark on the harmonic balancer aligns with the timing pointer on the engine block. This shows you the current timing advance.
2. Distributor: The distributor houses the rotor and the ignition module. Rotating the distributor advances or retards the ignition timing. This is done *mechanically*.
3. Specifications: You absolutely need the correct timing specification for your specific engine. This is typically found in your owner's manual or a reputable repair manual (like a Haynes or Chilton manual). The specification will usually be something like "10 degrees BTDC at idle" (Before Top Dead Center). The "at idle" part is very important, as timing changes with engine RPM.
4. Procedure (In short – always consult a repair manual for detailed steps):
* Engine running: The engine must be running at the specified idle speed.
* Timing light connected: Properly connect the timing light to the #1 spark plug wire and to the battery.
* Observe timing mark: With the engine idling and the timing light illuminating the harmonic balancer, observe where the timing mark sits relative to the timing pointer.
* Adjust the distributor: Loosen the distributor clamp slightly. Rotate the distributor slightly (clockwise usually advances timing, counter-clockwise usually retards it). Observe the change in the timing mark with the timing light.
* Iterative adjustment: Make small adjustments to the distributor and check the timing mark after each adjustment until it matches the specification.
* Tighten the clamp: Once the timing is correct, tighten the distributor clamp securely.
WARNING: Incorrect timing can damage your engine. If you are not comfortable performing this procedure, take your vehicle to a qualified mechanic. Improper adjustment can lead to poor engine performance, overheating, and even catastrophic engine failure. This is a simplified explanation and detailed instructions should be followed from a reliable source like a repair manual.
