Originally Posted by fivewindowcoupe
I've traced the knock to the passenger side either the #6 or#8 cylinder. *snip* I broke the engine in as per GM's instructions but I only went to 4000 - 45000 rom instead of the 5000 rpm spec'd by GM.
I would suggest you pull the valve cover and carefully check the valve lash on the suspect valves, and readjust them just as you originally did.
If the tapping diminishes then returns yet again- there's a good chance a cam lobe is going away.
Is there a reason you didn't follow GM's instructions regarding break-in?