1. What is Valve Lift?

Valve lift is the maximum distance the valve moves away from its seat during the camshaft's rotation. It's determined by multiplying the camshaft lobe lift by the rocker arm ratio.

2. How Does the Calculator Work?

The calculator uses the valve lift formula:

Where:

• Cam Lift — The maximum lift of the camshaft lobe (mm)
• Rocker Ratio — The mechanical advantage of the rocker arm (dimensionless)

Explanation: The rocker arm multiplies the cam lobe's movement to create greater valve lift than the cam lobe alone would produce.

3. Importance of Valve Lift Calculation

Details: Proper valve lift is crucial for engine performance, affecting airflow into and out of the combustion chamber. Too much lift can cause valve-to-piston interference, while too little can restrict airflow.

4. Using the Calculator

Tips: Enter cam lift in millimeters and the rocker arm ratio (typically between 1.1 and 1.8 for most engines). Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical rocker arm ratio?
A: Most production engines use ratios between 1.5:1 and 1.7:1, though performance engines may use higher ratios.

Q2: How does valve lift affect engine performance?
A: Increased valve lift generally improves airflow and power, but only up to the point where the port becomes the flow restriction.

Q3: Can I measure rocker ratio directly?
A: Yes, by measuring the distance from the rocker pivot to the valve contact point and comparing it to the distance from the pivot to the pushrod contact point.

Q4: What factors limit maximum valve lift?
A: Valve spring pressure, piston-to-valve clearance, and the camshaft's ability to maintain valve acceleration profiles at high RPM.

Q5: Does valve lift affect duration?
A: While related, lift and duration are separate specifications. However, higher lift cams often have increased duration as well.