Clicking In The Engine

1972 Dodge Dart, 225, 3.7, 2BBL Holly, Mild Cam (Unknown Brand), Long Tube headers, Electronic Dist,

Question what I have is It sounds like a little clicking noice under the valve cover. does something need to be adjusted? Something that I can do? Also car drives great, starts great no problems just wondering about the noice because you can hear it when I have the hood open. Thanks Everyone!