Here's a general outline. Always consult a factory service manual for your specific engine for exact specifications and procedures. The manual will have torque specifications and diagrams crucial to the process.
Tools You'll Need:
* Factory Service Manual: Absolutely essential.
* Valve Lash Adjusting Tool: This is a special tool with a feeler gauge built-in, designed to accurately measure and adjust the lash. A standard feeler gauge is insufficient.
* Socket Set: Various sizes to remove and install the rocker arms, as needed.
* Wrench Set: For various bolts and nuts.
* Torque Wrench: Critical for tightening components to the correct specification.
* Feeler Gauges: For double-checking the lash after adjustment (though your valve lash tool should have this built-in).
* Breaker Bar: May be needed to loosen stubborn rocker arm nuts.
* Safety Glasses: Protect your eyes.
* Gloves: Protect your hands.
* Clean Rags: To keep things clean.
Procedure (General Outline – Consult your Service Manual):
1. Safety First: Disconnect the negative battery terminal.
2. Access: Gain access to the valve train. This usually involves removing parts like the valve cover. Your service manual will detail this process.
3. Engine Positioning: You'll need to rotate the engine crankshaft to position each piston at Top Dead Center (TDC) on the compression stroke for each cylinder. This is crucial for accurate valve lash adjustment. Your service manual will explain how to do this using the timing marks or a degree wheel. There will be a specific firing order for the engine that must be followed.
4. Loosen Rocker Arm Nuts: Carefully loosen the rocker arm nuts for the intake and exhaust valves of each cylinder *before* you adjust them.
5. Adjust Valve Lash: Using your valve lash adjusting tool, adjust the lash to the factory-specified clearance. This clearance will be different for the intake and exhaust valves and is critical to get correct. The manual specifies the precise clearance in millimeters or thousandths of an inch. Your tool will help you find the correct feeler gauge size. *Tighten the adjusting nut only after confirming the correct clearance with your tool.*
6. Repeat: Repeat steps 3-5 for each cylinder, ensuring that the engine is at TDC on the compression stroke for each cylinder before adjusting the valve lash.
7. Torque Specification: Once the lash is correctly set, tighten the rocker arm nuts to the manufacturer's specified torque using a torque wrench. This is vital to prevent damage.
8. Reassembly: Carefully reassemble all removed components.
9. Recheck: After reassembly, consider rechecking the valve lash to ensure the adjustments held.
Important Considerations:
* Hydraulic Lifters: The 7.3 IDI does *not* use hydraulic lifters. This means you must adjust the valve lash manually and periodically.
* Engine Temperature: The engine should be at operating temperature (or close to it) for accurate adjustments. The metal will expand and the clearance will change as it warms up. Check your service manual for precise instructions.
* Factory Specifications: Never deviate from the specifications provided in your factory service manual. Using incorrect clearances can cause serious damage.
Again, I strongly recommend obtaining and carefully following a factory service manual for your specific 1989 Ford 7.3L IDI engine. This information is a general guideline and may not cover all specific details or potential variations. Improperly adjusting valve lash can lead to costly engine damage. If you are not comfortable with this task, seek the help of a qualified mechanic.
