How To Adjust The Valves On A 350 Chevy

How to Adjust Valves on a 350 Chevy Small Block Engine

This guide provides a comprehensive walkthrough on how to adjust the valves on a 350 Chevy small block engine. This is a crucial maintenance task to ensure optimal engine performance and longevity. Improper valve adjustment can lead to decreased power, poor fuel economy, and even engine damage. So, let's dive in!

Tools You'll Need

Before you begin, gather the necessary tools. This will make the process smoother and more efficient. You'll need:

• Valve Adjusting Wrench: Specifically sized for your valve cover's adjusting screws.
• Feeler Gauges: A set covering the specified valve clearance range for your engine (consult your owner's manual).
• Socket Wrench and Extensions: To remove and install the valve covers.
• Wrench for Distributor Hold-Down Clamp (Optional): Helps prevent accidental distributor rotation.
• Shop Rags: To keep the engine clean.
• Owner's Manual: Crucial for accurate specifications.
• Mechanic's Gloves: Protecting your hands is always a good idea!

Understanding Valve Adjustment

Valve adjustment ensures proper clearance between the valve stem and the rocker arm. Too much clearance (loose valves) results in noisy operation and lost power. Too little clearance (tight valves) can cause valves to burn, leading to serious engine damage. The goal is to achieve the precise clearance specified in your engine's manual.

What's the Difference Between Hydraulic and Mechanical Lifters?

The process slightly differs depending on whether your 350 Chevy uses hydraulic or mechanical lifters.

• Hydraulic Lifters: These automatically adjust valve clearance. While they don't require routine adjustments like mechanical lifters, they can still benefit from periodic checks to ensure they're functioning correctly. Unusual noises may indicate a problem.

• Mechanical Lifters: These require regular adjustment, typically every few thousand miles, depending on driving style and engine use. This guide focuses on adjusting engines with mechanical lifters. Refer to your owner's manual for specifics.

Step-by-Step Valve Adjustment Procedure (Mechanical Lifters)

Safety First! Always disconnect the negative battery terminal before starting any engine work.

1. Preparation: Park your vehicle on a level surface, engage the parking brake, and allow the engine to cool completely. This is critical for your safety.

2. Remove Valve Covers: Carefully remove the valve covers using the appropriate socket wrench and extensions. Clean any accumulated dirt or debris.

3. Locate the Rocker Arms: Identify the intake and exhaust rocker arms for each cylinder.

4. Rotate the Engine: Use a wrench on the crankshaft pulley or harmonic balancer to slowly rotate the engine. This is done to position each cylinder's piston at top dead center (TDC) on the compression stroke. You need to align the timing marks on the crankshaft pulley and timing cover. Your owner's manual will detail how to properly identify TDC. This is a crucial step to ensure correct valve adjustment.

5. Adjusting the Valves:

   • Set the Feeler Gauge: Insert the correct feeler gauge (as per your owner's manual) between the valve stem and the rocker arm.
   • Adjust the Rocker Arm: Tighten the adjusting screw until the feeler gauge feels snug but can still be moved. Do not over-tighten.
   • Repeat: Repeat this process for each valve on the engine, making sure to rotate the engine to the correct TDC for each cylinder in sequence.

6. Double-Check: After completing the adjustments, double-check each valve again to ensure the correct clearance.

7. Reinstall Valve Covers: Carefully reinstall the valve covers, ensuring a proper seal.

8. Reconnect Battery: Reconnect the negative battery terminal.

9. Start the Engine: Start the engine and listen for any unusual noises.

Troubleshooting

If you encounter persistent valve train noise after adjustment, there may be other issues, such as worn rocker arms, lifters, or camshaft. It may be necessary to seek professional help in this situation.

Conclusion

Adjusting valves on a 350 Chevy small block engine is a vital maintenance task. Following these steps carefully and consulting your owner's manual will ensure your engine runs smoothly and efficiently. Remember, safety is paramount, so take your time and work methodically. If you're unsure about any step, it's always best to seek the assistance of a qualified mechanic.