How to Set the Timing on a Jeep Wranglerby Chris Orr
AMC introduced the redesigned Jeep Wrangler in 1987 and built the model for one year before the company was bought by Chrysler. Early Jeep Wranglers that were equipped with the 2.5-liter four-cylinder and the 4.2-liter six-cylinder engine had carburetors before Chrysler began producing Jeeps with computerized fuel injection. Correct timing on a carbureted Jeep Wrangler ensures smooth driving on and off-road.
Set the parking brake and start the engine of the Jeep Wrangler. Let the engine warm up to its normal operating temperature. Maintain the appropriate idle speed, which will depend on your transmission. For a manual transmission, the idle speed is 680 rpm; for an automatic transmission, the idle speed is about 600 rpm.
Open the hood of the Jeep Wrangler and disconnect the vacuum advance hose from the distributor with your hand. Seal off the hose using a vacuum plug. Disconnect the electrical connector from the CEC system switch assembly, located on the top of the valve cover.
Locate the engine timing marks. The timing marks are found on the top of the engine, on the crankshaft pulley or the vibration damper. Use chalk to mark the groove on the pulley or damper and the point on the scale that corresponds to the correct engine timing as per the Vehicle Emission Control label.
Connect the timing light. The power leads on the timing light should be connected to the battery terminals and the pickup lead connects to the #1 cylinder spark plug.
Point the light at the chalk mark on the pulley/damper and check the timing. The mark will appear stationary relative to the timing scale. If it is aligned with the mark on the scale, the engine timing is correct. If it is not aligned, the timing needs adjustment.
Adjust the engine timing if necessary. Using the distributor wrench, loosen the hold-down bolt on the distributor housing and slowly turn the distributor until the marks are aligned. Re-tighten the bolt and recheck the timing. If the marks are aligned, turn off the engine and reconnect the vacuum advance hose and CEC electrical connector. If the marks are not aligned, repeat this step, making incremental adjustments until the marks are properly aligned.
Items you will need
- Vacuum plugs
- Timing light
- Distributor wrench
- "Haynes Repair Manual: Jeep Wrangler 1987 thru 2008"; Mike Stubblefield and John Haynes; 2009
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