To calculate the cam timing, you need to measure the duration of the intake, duration of the exhaust, the lobe separation angle of the camshaft, and the degree of advance the camshaft is installed at.

The camshaft's advance is calculated by subtracting the intake lobe centerline in degrees from the lobe separation angle. If the number is positive, the camshaft is considered “advanced”, if it is negative it is considered “retarded”, if the result is 0 it is considered “straight up”. The calculator will provide the intake and exhaust valve events based on these measurements.

The intake centerline is calculated as the lobe separation angle minus the advance; the exhaust centerline is the lobe separation angle plus the advance. The intake valve opening (IVO) is calculated as half of the intake duration plus the advance minus the lobe separation angle, while the intake valve closing (IVC) is half of the intake duration minus the advance plus the lobe separation angle minus 180 degrees. The exhaust valve opening (EVO) is calculated as half of the exhaust duration plus the advance plus the lobe separation angle minus 180 degrees, and the exhaust valve closing (EVC) is half of the exhaust duration minus the advance minus the lobe separation angle. The valve overlap is calculated as the sum of half the intake duration and half the exhaust duration minus twice the lobe separation angle.

By entering the intake duration, exhaust duration, and lobe separation angle into the calculator, it will perform the necessary calculations to provide the cam timing events.