Rockers and why would you adjust them

[Urge38]

Open debate question, 

as of right now, I have no opinions on either, hence my question and wishing to learn

I've never owned a hydraulic lifter, 

But I can't help but wonder, why are they hydraulic and self-adjusting if they need adjusting?????


I get that one would set the rocker from new, or after a issue, ie cam replacement, but i cant understand why you would adjust them because or wear and tear, surly there is a need to replace something first as that contradicts the design off a self-adjusting lifter 


its obvious that adjusting a wore rocker will bring some things back into spec (ish) that does not need to be mentioned, but arnt you masking something that's worn??

[silverbullet]

The valve stem and the rocker screw tips both wear, top end lubrication is marginal on any VW flat 4

[Simon Baxter]

As I understand them, when they are new and empty/soft then you need to give them a basic setting to work from, that's the one mentioned in the Haynes where you screw the adjuster down until the adjuster screw just touches then you go a further 2 full turns.
I believe that then gives the hydraulic tappet/lifter/whatever enough scope to automatically adjust either way.
Once they are pumped up then in my experience the 2 turns is out of the window, if for whatever reason you need to "adjust" a lifter then I used to go a turn to a turn and a quarter, that usually worked.
Going 2 turns on a pumped up lifter is a recipe for a lot of cranking, low compression and a flooded engine.