Step-by-step guide: how to determine valve lash on your sbc

Maintaining optimal engine performance requires regular valve lash adjustments. For small block Chevrolet (SBC) engines, checking and adjusting valve lash is a crucial procedure to ensure proper valve operation and engine efficiency. In this comprehensive guide, we’ll delve into the step-by-step process of checking valve lash on an SBC, empowering you with the knowledge to perform this essential maintenance task.

What is Valve Lash?

Valve lash, also known as valve clearance, refers to the precise gap between the valve stem and the rocker arm. This gap allows for thermal expansion and contraction of the engine components, ensuring that the valves can open and close smoothly without binding.

Symptoms of Incorrect Valve Lash

Improper valve lash can lead to a range of performance issues, including:

• Reduced engine power
• Increased fuel consumption
• Excessive engine noise
• Poor idle quality

Tools Required

To check valve lash, you’ll need the following tools:

• Feeler gauge
• Socket wrench
• Ratchet
• Screwdriver

Step-by-Step Procedure

1. Prepare the Engine

• Allow the engine to cool completely.
• Remove the spark plugs for easier access to the rocker arms.

2. Locate the Rocker Arms

• Identify the rocker arms responsible for operating the intake and exhaust valves.

3. Set the Engine to TDC

• Rotate the crankshaft until the piston for the cylinder you’re adjusting is at top dead center (TDC).
• Check this by inserting a screwdriver into the spark plug hole and feeling for the piston to be at its highest point.

4. Check the Intake Valve Lash

• Using a feeler gauge, measure the gap between the intake valve stem and the rocker arm.
• The correct lash specification for SBC engines is typically between 0.006 and 0.008 inches.
• If the gap is too small, the valve will not open fully, reducing engine performance.
• If the gap is too large, the valve may not close properly, causing excessive noise and potential damage.

5. Adjust the Intake Valve Lash

• If necessary, adjust the intake valve lash by loosening the rocker arm nut and rotating the pushrod until the correct gap is achieved.
• Tighten the nut securely.

6. Check the Exhaust Valve Lash

• Repeat the same procedure to check and adjust the exhaust valve lash.

7. Rotate the Crankshaft

• Rotate the crankshaft 360 degrees to bring the next cylinder to TDC.
• Repeat steps 4-6 for each remaining cylinder.

Wrap-Up

Checking and adjusting valve lash on an SBC engine is a straightforward procedure that can significantly improve engine performance and longevity. By following these steps carefully, you can ensure that your SBC engine operates at its optimal level for years to come.

Answers to Your Most Common Questions

Q: How often should I check valve lash on my SBC engine?
A: Valve lash should be checked every 3,000-5,000 miles or as recommended by your vehicle’s manufacturer.

Q: What happens if I ignore valve lash adjustments?
A: Ignoring valve lash adjustments can lead to reduced engine power, increased fuel consumption, and potential damage to the engine valves.

Q: Can I adjust valve lash with the engine running?
A: No, valve lash should always be adjusted with the engine off and cool.