Base Timing

Inspect timing indicator and crankshaft pulley mark. Clean marks if necessary and warm engine to normal operating temperature. Ensure idle speed is within specification. See IDLE SPEED SPECIFICATIONS table. Turn all accessories off. Attach timing light to No. 1 spark plug wire.
Aim timing light at crankshaft pulley. If timing is not within specification, loosen distributor hold-down bolt and rotate distributor to obtain correct ignition timing. See IGNITION TIMING SPECIFICATIONS table. Tighten distributor hold-down bolt and recheck timing.

Fig 1: Idle Speed Control (ISC) Connector Location

Courtesy of GENERAL MOTORS CORP.

Fig 2: Ignition Timing Mark Location

Courtesy of GENERAL MOTORS CORP.

IGNITION TIMING SPECIFICATIONS (Degrees BTDC @ RPM)

Application	Man. Trans.	Auto. Trans.
1.5L	3 @ 650	3 @ 900