I've never adjusted the valves on a 2.1 except when rebuilding after 150K or so. (VW didn't even have valve adjustment on the maintenance schedule.) Otherwise the lifters should self-adjust enough to take up the wear, unless there is some other problem. So I'm curious, have you done a rebuild, is there a sign of a problem, or do you just feel it's time?
The reason for asking is that the lifters need to be fully filled with oil to get a good adjustment. If you are just doing a periodic adjustment on an engine, you would need to back off the adjustment to remove the preload, and that might leave an air pocket in the lifter, making it hard to set.
On a rebuild you carefully oil-fill the lifters before assembling to eliminate trapped air, assemble with the adjusters backed out, then set each set to just contact (zero lash) and add 1/2 to 2 turns to compress the hydraulic mechanism so they will self adjust.
If you find a lifter that has trapped air it won't feel solid when the adjuster touches, as the internal spring can easily compress without a solid oil fill. (This is also what happens if you back off the adjuster on a built engine.) Then you have to be real careful not to compress the lifter before adding the 1/2 to 2 turns, or you can bottom out the hydraulic and hold the valve open. It will take a while running with the oil good and hot (thin) for such lifters to pump up and quiet down.
If you are just doing a periodic valve adjustment (not recommended) I wouldn't touch any that don't have free play: just let the hydraulics do their job. If there is free play it could just be that the lifter has trapped air and hasn't pumped up, so you have to back off the adjustment and see if you can feel the lifter compress after you take up the gap. Again, go 1/2 to 2 turns after contact, not after compressing the lifter spring.
Bob Donalds used to recommend adjusting first as if they were solid, by leaving a .004-6 gap and driving with the tick-tick until you were sure the lifters had pumped up, then go back and adjust to zero lash plus 1/2 turn compression.
It is a bit confusing until you develop a feel for what is happening; but once they are set right just leave them alone.

That make sense. I'll attempt this feat this afternoon once the sun warms up the driveway.

The van in question was a purchase from a broke DOT.Commer in the bay area of California which had a bad headgasket.
The head is complete and the van has made numerous trips up to my mt home in the Sierras but has a rattly lifter on the side that was repaired. I think I may of left the valves loose.

I also now wished I had replaced the hydro lifters when the head was off the engine.