Rocker Arm Options

Understanding Rocker Arm Ratio​

The rocker arm is the lever that transfers camshaft lobe motion to the valve. Its ratio determines how much the valve actually opens relative to the cam lobe lift. A 1.5:1 rocker arm multiplies the cam lobe lift by 1.5 — so a cam with 0.250" lobe lift produces 0.375" of valve lift (0.250 × 1.5 = 0.375").

Upgrading to a higher-ratio rocker arm is one of the most cost-effective ways to increase valve lift without changing the...