Oil pump shaft question

We use a 3 bolt cam with a button if you want to know. A special cover is used also if you want to control cam movement. I thought we were talking small block here. Wonder what holds the cam rearward with out the button on a tappet motor. Must be lifter rotation as I said earlier. Also big blocks never came with a roller from the factory as the small blocks did. Nor did the Hemi's.