1992 Buick Roadmaster set ignition timing

Place transmission in Park. Start and warm engine to normal operating temperature. Turn A/C and all accessories off. Ensure CHECK ENGINE light is off.
Put Electronic Spark Timing (EST) into by-pass mode by unplugging Set-Timing connector. Connector is a single wire in wiring harness near distributor or right shock tower. DO NOT unplug 4-wire connector at distributor.
Connect timing light to spark plug No. 1 wire. Loosen distributor hold-down bolt. Set timing to specification. Refer to the V8 IGNITION TIMING SPECIFICATIONS below. Tighten distributor, and recheck timing. Reconnect Set-Timing connector. Clear Electronic Control Module (ECM) trouble code by momentarily disconnecting ECM power source or negative battery terminal.