* Specific engine configuration: The exact specifications of the 454 (e.g., carbureted, TBI, specific emission control setup) will affect the ideal timing.
* Fuel type: The octane rating of the fuel used influences the ignition timing.
* Engine condition: Worn components can require adjustments to the timing.
* Altitude: Higher altitudes may necessitate timing adjustments.
Instead of a single number, you need to consult your vehicle's owner's manual or a repair manual specific to your 1989 Suburban's 454 engine. These manuals will provide the base timing specification and instructions on how to set it using a timing light. They will also likely include information on adjusting timing based on engine performance.
Trying to guess the timing can damage your engine. Incorrect timing can lead to reduced power, poor fuel economy, overheating, and even engine damage. Use a reliable resource for the correct timing setting and procedure.
