Would a "chattering sound" coming from under a valve cover mean loose rocker arms?

Sorry if that's a dumb question, but I've never ran into this before personally. I haven't adjusted the valve lash sence I assembled the engine. (I used the method in the Haynes Manuel)

 

very possible. It would not hurt to pull the covers off and check.

 

Exactly what it sounds like. If you notice one is loose, go ahead and adjust it back to spec. most importantly, if this happened over time, make sure to replace the nut! otherwise youll be pulling the valve covers back off in a week lol

 

Hopefully it's just the rocker, and not a lifter!

 

If its been doing it all along then you may have had them too tight from when you first assembled the engine.

A friend of mine had assembled his engine and ran it for a whole year before he decided to have me adjust his rock solid lifters that ticked like crazy. They adjusted just fine and no ticking afterwards.