How To Measure Pushrod Length

How to Measure Pushrod Length: A Comprehensive Guide

Knowing how to accurately measure pushrod length is crucial for optimal engine performance. Incorrect pushrod length can lead to a range of problems, from decreased valve lift to premature wear and even engine damage. This guide provides a clear, step-by-step process to ensure you get it right.

Why Accurate Pushrod Length Matters

The pushrods are the mechanical link between your rocker arms and camshaft. They transfer the motion of the cam lobes to open and close your engine's valves. Incorrect length directly impacts valve timing and lift, which are fundamental to engine efficiency and power.

Consequences of Incorrect Pushrod Length:

• Reduced valve lift: This limits the engine's ability to breathe efficiently, leading to a loss of power and performance.
• Premature valve train wear: Incorrect geometry puts extra stress on components, shortening their lifespan.
• Valve float: At high RPMs, the valves might not close completely, leading to poor combustion and potential engine damage.
• Noise: Clicking or ticking sounds often indicate incorrect pushrod length.

Tools You'll Need

Before you begin, gather these essential tools:

• Pushrod length measuring tool: While a ruler can be used, a dedicated tool is far more accurate and provides a consistent measuring surface.
• Dial indicator: This precision instrument will help determine the correct pushrod length.
• Feeler gauge: Necessary for setting valve lash or preload (depending on your engine setup).
• Appropriate socket and wrench: For removing and installing the rocker arms and pushrods.

Step-by-Step Guide to Measuring Pushrod Length

This guide assumes you have already removed the rocker arms and pushrods from the engine. If not, consult your engine's service manual for proper disassembly procedures.

1. Prepare the Engine: Ensure the engine is at top dead center (TDC) for the cylinder you're working on. This is crucial for accurate measurements. Use a degree wheel or your engine's timing marks to verify TDC.

2. Set Valve Lash/Preload: Using the feeler gauge, set the correct valve lash or preload according to your engine's specifications. This is a critical step to ensure accurate measurements. Consult your engine's service manual for the precise specifications.

3. Insert the Pushrod: Carefully insert a pushrod into the valve lifter and rocker arm.

4. Measure with the Dial Indicator: Place the dial indicator on the rocker arm, ensuring it's firmly positioned and making good contact. Zero the indicator.

5. Adjust and Measure: Gently push down on the rocker arm using the dial indicator until you achieve the specified valve lash/preload. Note the distance between the rocker arm and the valve stem. This is where your pushrod length measuring tool comes into play; it will help you determine the needed length accurately.

6. Calculate Required Pushrod Length: Subtract the pushrod measurement from the total distance, which will give you the required pushrod length. Remember to account for any differences between the pushrod's ends (ball, cup, etc.)

7. Repeat for All Cylinders: Repeat steps 3-6 for all cylinders to ensure consistent valve train geometry. Slight variations between cylinders are normal, but extreme differences require further investigation.

Troubleshooting and Tips

• Consult your engine's service manual: Always refer to your engine's service manual for specific procedures and specifications.
• Precision is key: Accurate measurements are essential for optimal performance.
• Use high-quality tools: Invest in good quality measuring instruments.
• Double-check your work: Always verify your measurements to avoid mistakes.

By following these steps carefully, you can accurately measure pushrod length and ensure your engine's valve train is operating efficiently and reliably. Remember to prioritize safety and consult your engine's service manual for any specific instructions.