Why does the Valve Timing Calculator show 4º of advance when I installed the cam straight up?
Cam timing is always referenced to the crankshaft. That is, the installed intake centerline (ICL) is always in degrees after top dead center. Some cams are manufactured with some amount of advance built into them, 4º is very common. In this case, if the cam is installed with the timing gear marks lined up for “0” advance, the cam is actually installed with 4º of advance. While the timing set may say the cam is straight up, it is, in reality, installed with 4º of advance. The program (or engine, for that matter) doesn’t know or care what the timing set is installed at, it only cares where the ICL is in relation to the crankshaft.
