tappin sound

[dockdriver939]

I got this tapping coming from my head (s13 sr redtop). I took the valve cover off and it sounds like its coming from the exhaust side under the cam but everthing looks fine and it runs fine but at 2500 rpm it sounds pretty bad. nothing done to the motor perfomace wise. Thinking of just rebuilding the head but figured i would ask before i tore it apart. Any help is much appr. thanks in advance

[KiLLeR2001]

probably lifters needing to be bled, mine also make a tapping noise but seems to go away when the car warms up and only at certain rpms will i hear it, and its not the timing chain rattle