How to judge the compression top dead center of 1 cylinder for 465 engine? Please explain clearly what the lower lobe of camshaft means.

When the cam is viewed from the horizontal position, that is, from the axial direction, if it is shown in the following figure, it is at the compression top dead center, that is, the valve rocker arm falls on the base circle of the cam. The first eight are that the intake and exhaust valves are closed, and the last eight are that the intake and exhaust valves are only opened a little. The most stupid way is to remove the high-pressure tubing, which is the compression top dead center after injection.