[Jerry Clayton]

all the engines I've seen that had loose valve seats were ----------------------------

IF--------the valve seat isn't installed with the proper interference fit----AND --------the engine is shut off with the exhaust valve somewhat (only a little bit) open (off the seat) the seat could possibly drop down out of the casting, and would after the engine has cooled off---would cause excessive valve tappet clearance which would then be a noise you could hear-

Suggestion is to remove the valve cover and check valve clearances-if you find excessive clearance then look for the cause-----

Of course, if you are running flat tappets, it could be a lobe wiped out---------