* Engine condition: Worn components, carbon buildup, and vacuum leaks will all affect optimal timing.
* Altitude: Higher altitudes require slightly less advance.
* Fuel: The type of fuel used can influence the ideal timing.
* Modifications: Any aftermarket parts (camshaft, intake manifold, etc.) will change the ideal timing.
The factory specification likely falls within a range, perhaps 6-10 degrees BTDC (Before Top Dead Center) at idle. However, simply aiming for a number on the timing scale isn't the right approach. You need to verify the timing using a timing light with the engine at idle and at operating temperature.
Here's how to find the ideal timing for *your* engine:
1. Consult your owner's manual or a Buick repair manual: This should provide the factory-recommended idle timing range for your specific engine.
2. Set the idle speed: Make sure the engine is idling smoothly at the manufacturer's specified RPM (usually around 750 RPM).
3. Connect a timing light: Properly connect a timing light to the #1 cylinder spark plug wire and your engine's timing mark (usually a pointer on the harmonic balancer).
4. Observe the timing: With the engine running at idle, aim the timing light at the timing marks. The number indicated should be within the factory range.
5. Adjust the distributor: If the timing is outside the specified range, adjust the distributor to achieve the correct timing. You may need to loosen the distributor hold-down clamp slightly. Small adjustments are key – rotate the distributor slightly and re-check the timing until it falls within the specified range. *This should be done carefully*.
6. Fine tune: After adjusting the timing, retest the engine's performance, and re-adjust if necessary. The best timing will allow the engine to run smoothly and efficiently with good acceleration.
Going "a notch past 20" suggests your timing is significantly advanced, potentially causing damage (pinging/knocking, overheating). This is *not* recommended. The best approach is to start with the factory specification and adjust from there based on engine performance. If you're unsure, seek help from a qualified mechanic familiar with older vehicles.
