Probably a bad lifter period. I wouldn't worry about it. There are some additives out there, but the only legitimate co. that comes to mind is "Lucas". I'm not sure if they make a detergent though.
Threre's a million opinions on additives, so no flame intended.
When it's cold and my car has been sitting for a day or so, it will make lifter noise for a few secs. I ran a detergent (name escapes me) and did nothing.
The valves on the M117 aren't adustable.
Also, how many miles? My clatter started at about 90k in near 0-15F temps.