Quote: The lifter has to be harder because it has load on one contact point all the time, where as the cams contact loaded point is spread all around the cams lobe.
The cam lob has a slight taper and the lifter has a slight 'dome'. The lifter does not contact the full face of the lifter or vice versa. The lifter also is supposed to spin as th cam shaft rotates so that the contact patch is not constant. If the lifter does not spin in the bore the cam and lifter will be destroyed in very short order.
The point I was making is the load is focused on one small area on the lifter but spread out all over the lobe. Sure the lifter spins which helps to spread the load, but it is still a concentrated area compared to the lobe.
