* Engine modifications: Has the engine been modified with different camshafts, heads, intake manifolds, or carburetors? Modifications significantly affect optimal timing.
* Fuel type: The type of gasoline used (regular, premium, etc.) can influence ignition timing.
* Altitude: Higher altitudes require different timing.
* Vacuum advance: The vacuum advance mechanism on the distributor plays a crucial role and its proper function is essential.
Instead of a specific number, the correct procedure is this:
1. Consult your owner's manual (if you have it): This is the best starting point, as it should specify the initial timing for your *specific* 1972 Ford 460.
2. Use a timing light: This is essential for accurately setting the ignition timing.
3. Set the initial timing: This is typically done with the engine idling at a specified RPM (usually around 600-800 RPM) and with the vacuum advance disconnected. The owner's manual or a Ford 460-specific repair manual will give you the base timing specification. This is usually around 10-12 degrees BTDC (Before Top Dead Center), but this is just a starting point.
4. Reconnect the vacuum advance: Once the initial timing is set, reconnect the vacuum advance.
5. Check total timing: This is the timing at higher RPMs. A timing light and a tachometer are needed to check the total timing. Again, your owner's manual or a repair manual should give you the ideal total timing advance. Total timing is usually in the 30-36 degrees range, but this will depend on the factors listed above.
6. Fine-tune (if necessary): Once the timing is set, you may want to fine-tune it based on how the engine runs. You can usually adjust it a couple of degrees in either direction to optimize performance and emissions. A vacuum gauge can be a useful tool in fine-tuning timing.
Without knowing your engine's specific condition and modifications, any specific timing number I give you would be potentially harmful to your engine. Consult a reliable Ford 460 repair manual or a qualified mechanic to get the proper timing for your vehicle.
