HEI-Est Distributor: Notes
WARNING: This page does not describe the selected car, but rather 34 other vehicles, including the 1991 Pontiac Sunbird, 1991 Pontiac Grand Prix, 1991 Pontiac Grand Am, 1991 Pontiac Firebird, and 1991 Pontiac Bonneville. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
The only adjustments that can be made to HEI/EST ignition system are basic ignition timing (on distributor-type ignitions) and spark plug gap.