Spark Plug - Usage
NUMBER: 86-B-104GROUP: 6D - Engine Electrical
DATE: July, 1986
SUBJECT: SPARK PLUG USAGE
MODELS: 1986 LIGHT DUTY VEHICLES
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 range 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
M 2.5L E R43CTS6 0.060 5613812
M 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