Cam Lobe Lift Measurement Diagram - Calculate Valve Lift by Rocker Ratio

This document is a simple technical sketch/schematic showing how to measure a camshaft lobe to determine valve lift. The drawing depicts a single cam lobe (egg-shaped profile) with three dimension callouts: A is the overall lobe height from nose to base circle, B is the base circle diameter (lobe width), and C represents the resulting lobe lift. The accompanying instructions state that subtracting B from A gives C, the lobe lift. That lobe lift value is then multiplied by the rocker arm ratio to obtain gross valve lift: multiply by 1.73 for a hydraulic cam rocker ratio (result D), or by 1.76 for a solid cam rocker ratio (result E). The note also instructs the user to perform this measurement on both intake and exhaust lobes if the camshaft is a dual-pattern grind (different intake and exhaust profiles). This is a general cam-measurement reference; it was uploaded to a 1966 Ford Fairlane gallery alongside FE engine firing order and clutch Z-bar diagrams, but the sketch itself lists no specific year, make, model, or part numbers. A reader can learn the basic method for calculating valve lift from a camshaft removed from (or measured in) an engine using simple external measurements.