how to adjust Ignition time on a 1990 trans sport?

To adjust the ignition timing on a 1990 Pontiac Trans Sport, first, ensure the engine is at operating temperature and then turn off all electrical accessories. Locate the timing mark on the harmonic balancer and the timing tab on the engine. Use a timing light to check the timing; if adjustment is needed, loosen the distributor hold-down bolt and rotate the distributor slightly until the desired timing is achieved, then retighten the bolt. Always refer to the vehicle's service manual for the specific timing specifications and procedures.