Series Trucks: 1989-90 C5, C6, C7 With 6.01 (LSO) 1990-91 C5H, C6H, C7H With 7.01 (LRO) 1990-91 P6, B6 With 6.OL (LSO)
Your 1991 Medium Duty Truck Service Manual shows the following maintenance and lubrication schedule for timing and distributor cap service. It reads:
MILES OR MONTHS | PAGE # | ITEM # --------------------|----------------|--------------- 24,000 / 24 | 0B-8 | A-28 27,000 / 27 | 0B-9 | A-28 60,000 / 60 | 0B-14 | A-28 --------------------|----------------|---------------
Instructions A-28- Timing and Distributor Cap service reads "Adjust Ignition Timing following the underhood label specifications. Also, carefully inspect the interior and exterior of the distributor cap, distributor rotor and inspect coil for cracks and terminal corrosion. Clean or replace as necessary." If replacement of the distributor cap is necessary, a new more robust cap is now available. The Part Number is 10474757 which is currently available from CANSPO.
Use applicable Labour Operation and Labour Time.
General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.