1. What is the Wall Rocker Arm Ratio?

The Wall Rocker Arm Ratio is a measurement that compares the valve lift to the cam lift in an engine's valvetrain system. It helps determine the mechanical advantage of the rocker arm assembly.

2. How Does the Calculator Work?

The calculator uses the Wall method formula:

Where:

• \( Valve\ Lift \) — Maximum lift at the valve (mm)
• \( Cam\ Lift \) — Maximum lift at the cam lobe (mm)

Explanation: The ratio shows how much the rocker arm multiplies the cam lobe's movement to produce greater valve lift.

3. Importance of Rocker Arm Ratio

Details: Knowing the rocker arm ratio is essential for engine builders to properly select camshafts, predict valve lift, and ensure proper valvetrain geometry.

4. Using the Calculator

Tips: Measure valve lift and cam lift accurately in millimeters. Both values must be greater than zero for a valid calculation.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical rocker arm ratio?
A: Most production engines have ratios between 1.5:1 and 1.8:1, though performance engines may use higher ratios.

Q2: How do I measure valve and cam lift?
A: Valve lift is measured at the valve stem, cam lift is measured at the lifter or follower. Use a dial indicator for accuracy.

Q3: Can the ratio be less than 1:1?
A: Yes, some engines use ratios less than 1:1 (called "de-magnification") to reduce valve lift while maintaining cam profile.

Q4: Does ratio affect valve timing?
A: No, the ratio only affects lift magnitude, not the timing or duration of valve opening.

Q5: How does ratio affect engine performance?
A: Higher ratios increase valve lift (potentially improving airflow) but may increase valvetrain stress and wear.