* Engine temperature: The timing is often specified at operating temperature (usually around 195-210°F or 90-99°C). The idle RPM can also slightly change with temperature.
* Vacuum: The vacuum advance contributes significantly to the total ignition timing. A failing vacuum advance can lead to significant timing errors.
* Distributor condition: A worn distributor can affect both timing accuracy and idle stability.
* Specific emission regulations: The exact specifications might have minor variations depending on the exact model and emission standards in the area the vehicle was sold.
Therefore, you cannot find precise numbers without consulting a reliable source for your specific vehicle. The best sources are:
* Your owner's manual: This is the most reliable source for factory specifications. Look for a section on specifications or engine tuning.
* A Ford shop manual (Haynes or Chilton): These provide detailed specifications and procedures for working on the engine.
* A reliable online database: Some databases, like those used by professional mechanics, contain this information. However, you need to be very careful about the source's reliability.
General Guidance (Use with Caution): While precise numbers are crucial, you might find general ranges cited in online forums or guides. Expect these to be approximations, and treat them with caution. Expect the initial base timing (before vacuum advance) to be in the range of 10-12 degrees BTDC (Before Top Dead Center). The idle speed should be around 650-800 RPM. However, these are merely estimations; they might not be correct for your specific engine.
Crucial Note: Incorrect timing can seriously damage your engine. If you are unsure about adjusting the ignition timing yourself, it's strongly recommended to take your vehicle to a qualified mechanic. They have the tools and knowledge to accurately set the timing and diagnose any underlying problems.
