Huh? You don't have tappets anywhere in that 2.6L engine, unless you consider the noises it makes with a maladjusted valve train. <img src="/forums/images/graemlins/smile.gif" alt="" />

The rotation you are talking about is for engines with tappets or lifters. The offcenter contact with the cam allows them to rotate in their bore. This is good for wear and lubrication.

I *think* you are talking about the rocker arms where they contact the valve stem. There is no way to get them to hit in the center all the time. Because the arm moves in an arc and the valve stem just moves vertically, the arm will move back and forth (relatively) on the valve stem.

Michael