When it comes to the Jeep CJ, spark plugs are very important. Equally as important are the type, quality, and performance ratings for the plugs you use.

When it comes to the Jeep CJ, spark plugs are very important. Equally as important are the type, quality, and performance ratings for the plugs you use. The spark plug delivers the spark from your Jeep’s ignition system to combust the fuel/air in the combustion cylinder in your engine. Typical spark plugs are going to consist of a threaded metal shell, which is insulated by a porcelain cover. This cover houses the central electrode. The spark plug is connected to the ignition system by the spark plug wire. Matching the right spark plug to the right Jeep CJ model is crucial to making sure your engine is operating at peak efficiency. When you do this, you are enabling your CJ’s engine to give you maximum output. If you’ve made some upgrades to the performance components of your engine, then a different spark plug might be required to accommodate the increased output from your upgrades. We’ve included this chart so that you can be sure that you are purchasing the absolute correct type of spark plug for your Jeep CJ.

Description

Type

Gap

5.9LNGK® or Champion® Copper Spark Plug0.035 in / 0.89 mm
5.0LNGK® or Champion® Copper Spark Plug0.035 in / 0.89 mm
4.2LNGK® or Champion® Copper Spark Plug0.035 in / 0.89 mm
2.5L (151 CU "Iron Duke") 1976-82NGK® or Champion® Copper Spark Plug0.060 in / 1.52 mm
2.5L (150 CU AMC) 1983-86NGK® or Champion® Copper Spark Plug0.035 in / 0.89 mm


Spark Plug Firing Order

Description

Firing Order

5.9L1-8-4-3-6-5-7-2
5.0L1-8-4-3-6-5-7-2
4.2L1-5-3-6-2-4
2.5L (151 CU "Iron Duke") 1976-821-3-4-2
2.5L (150 CU AMC) 1983-861-3-4-2