* Engine modifications: Modifications like camshafts, intake manifolds, exhaust systems, and computer tuning will significantly affect the ideal timing. Stock timing is different than modified.
* Fuel type: The type of fuel used (regular unleaded, premium, etc.) can influence the ideal timing.
* Altitude: Higher altitudes require different timing than sea level.
For a completely stock, unmodified 1988 Mustang 5.0L: The factory specification is typically around 10 degrees BTDC (Before Top Dead Center) at idle. However, this is a *starting point*.
Crucially: You should not rely solely on a number found online. Proper ignition timing requires a timing light and a procedure to set it accurately. The procedure generally involves:
1. Warming up the engine: The engine needs to be at operating temperature.
2. Connecting the timing light: Properly connect the timing light to the #1 spark plug wire and to a 12V power source.
3. Finding the timing marks: Locate the timing marks on the harmonic balancer and the timing pointer on the engine.
4. Adjusting the distributor: With the engine idling, adjust the distributor until the timing mark aligns with the specified timing degree. Your owner's manual will give a method of doing this.
Improper ignition timing can lead to serious engine damage. It's best to consult your owner's manual for the factory specification, and then use a timing light to set it correctly. If you're not comfortable performing this task yourself, take your car to a qualified mechanic. They will have the proper tools and expertise to do it safely and correctly.
