push rods are floating on my cv460s-26509

ok here it goes I brought a lt1000 craftsman tractor the head was removed and I don't know why yet so I brought a replacement head complete with all hardware and pushrods . they are non adjusting when I tighten down the rocker the pushrod is not tightening down its floating I can move the rocker up and down a half inch yet nothing is missing I don't know what is wrong I tried old head and new one same thing is there something I have to do to the cam or lifters thanks Scott