SPARK PLUG USAGE INFORMATION P/N'S AND GAP SETTINGS

Model and Year: 1986 LIGHT DUTY VEHICLES -------------- WITH GAS ENGINES

TO: ALL CHEVROLET DEALERS

The following information is being provided to assist dealers in the correct spark plug usage in 1986 Light Duty Trucks. Starting in 1986 many spark plug usages were changed. If it becomes necessary to replace the spark plugs, use the chart below for the correct plug application. It is not recommended that higher heat range plugs (example R43CTS to R44CTS) be substituted to try to correct a driveability complaint as installation of higher heat rangs plugs can cause engine damage.

MODEL ENGINE VIN CODE SPARK PLUG GAP P/N ----- ------- --------- ---------- --- ----- S/T 2.5L E R43CTS6 0.060 5613812 S/T 2.8L R R43CTS 0.045 5613810

MVan 2.5L E R43CTS6 0.060 5613812 MVan 4.3L Z R43CTS 0.035 5613810

C,K,G 4.3L N R43CTS 0.035 5613810 C,K,G 4.8L T R44T 0.035 5613867 C,K,G 5.0L H,F R43CTS 0.045 5613810 C,K,G 5.7L L,M R43CTS 0.045 5613810 C,K,G 7.4L W R44T 0.045 5613867

NOTE: Spark plugs should be ordered by part numbers. The plug type designation for a given part number may carry either a "C" or a dot "." to indicate a copper core electrode. AC-Delco is in the process of eliminating the "C" designation, and replacing it with a dot "." in all copper core plugs.

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.