if the tapping is continuous then you need to be concerned and open the valve covers now before damage can be done to the cam & rocker arm. if the tapping is left alone it can progress and possibly damage the cam. if it's only on startup then disappears in a few seconds maybe just maybe adding a detergent may work
mechanically if it's only a valve compensating element (ball stud or lifter) then for 30$ you can fix it. plus 5$ for the valve cover gasket. a cam costs about 275$ plus 8 new rocker arms etc:.
if you want to try the detergent route try either Marvel Mystery Oil or Rislone would be what i would add. run it a few miles maybe 50 if the noise does not disappear then it's mechanical and needs to be addressed.
i had this exact thing happen on my 88 last year and i left it tap away and it cost me that cam. all over only 1 ball stud.
good luck craig
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