1. Hydraulic Lifters:
Hydraulic lifters automatically adjust valve lash. You generally do not adjust them. However, you might need to check and correct for:
* Incorrect pushrod length: If you've changed camshafts, heads, or other components affecting valve train geometry, incorrect pushrod length is the most likely cause of needing "adjustment" in a hydraulic lifter setup. This manifests as noisy lifters (ticking). The solution is to measure and install the correct length pushrods. This isn't a rocker arm adjustment, but rather a prerequisite for proper hydraulic lifter function.
* Severe lifter wear or damage: A very worn or damaged lifter may fail to self-adjust correctly. Replacing the lifter(s) is the solution here, not adjustment of the rocker arms.
In short: With hydraulic lifters, focus on pushrod length and lifter condition. You don't adjust the rocker arms themselves.
2. Solid Lifters:
Solid lifters require periodic valve lash adjustment. This is done with the engine cold. Here's a general procedure, but always consult a shop manual specific to your engine and year:
Tools you'll need:
* Socket wrench and extensions: To remove the valve covers.
* Feeler gauges: To measure valve lash.
* Wrench or socket: To adjust the rocker arm adjusting nuts.
* Shop manual: For precise specifications on valve lash clearances for your camshaft. This is crucial, as incorrect lash can damage your engine.
* Torque wrench (optional but recommended): For precise tightening of rocker arm adjusting nuts.
Procedure:
1. Remove valve covers: This gives you access to the rocker arms.
2. Rotate the engine: Use the engine's crankshaft to rotate the engine slowly. You need to bring each cylinder to the correct position where the valves are fully closed. Your shop manual will indicate how to determine this (usually Top Dead Center – TDC – on the compression stroke).
3. Identify intake and exhaust valves: Each rocker arm adjusts a specific valve.
4. Measure valve lash: Using feeler gauges, measure the clearance between the rocker arm and valve stem for each valve (intake and exhaust). Your shop manual will provide the correct specification for your camshaft (usually given in thousandths of an inch, e.g., 0.016").
5. Adjust valve lash: If the clearance is incorrect, loosen the rocker arm adjusting nut slightly, then use the adjusting nut to set the correct clearance as measured by the feeler gauge.
6. Tighten the adjusting nut: Tighten the nut securely but don't over-tighten. A torque wrench is highly recommended to prevent damage. Consult your shop manual for the proper torque specification.
7. Repeat: Repeat steps 3-6 for all valves. You'll need to rotate the engine again and again to access each valve.
8. Reinstall valve covers: Once all valves are adjusted, replace the valve covers.
Important Considerations:
* Cold Engine: Always perform this adjustment with a cold engine. The engine's thermal expansion will alter valve lash.
* Shop Manual: Your shop manual is essential. It contains specific instructions, torque specifications, and valve lash clearances for your specific engine. Don't rely solely on generic instructions.
* Professional Help: If you are uncomfortable performing this task, it's best to have a qualified mechanic do it for you. Incorrect adjustment can lead to engine damage.
Remember, accuracy and precision are key to correctly adjusting solid lifter rocker arms. A small mistake can have significant consequences. If in doubt, consult a professional.
