Camshaft question

I would have to argue that the oil pump pushed against the cam. The oil pump may have resistance, but it cannot push or exert force, since it is the driven gear and not the drive gear. The cam lobe taper however, is what keeps the cam from walking in the block, when a thrust plate is not utilized. This is why roller cams must have a thrust plate or thrust button, because their lobes are not ground with taper.