SERVICE MANUAL UPDATE SEC. 6D4 SPARK PLUG GAP

SUBJECT: SERVICE MANUAL UPDATE - SECTION 6D4 SPARK PLUG GAP (REVISED SPECIFICATION)

VEHICLES AFFECTED: 1991 "S AND T" TRUCK WITH 4.3L ENGINE (VIN Z, RPO LB4)

The following represents revised information for SECTION 6D4 in the 1991 S/T service manuals.

This information replaces the plug gap information found under "Spark Plugs" in "Specifications."

The gap for plugs used in the 4.3L (LB4) (VIN Z) engine should be 0.035 inch, not 0.045 as stated in the manual. Torque remains as stated.

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.