Jim,
I'm new to the list but I've done my fair share of engine work over the
years. No, you don't adjust your hydraulic lifters. If they get too noisy
then perhaps there is some sort of dirt or obstruction to the bleed system
in the lifter causing it to partially or fully collapse. This makes a heck
of racket and if it's fully collapsed the valve may not be opening and
you'll lose that cylinders ability to function. Hence big loss of power in a
4 cylinder engine.

You can periodically, say every 50,000 miles, take the lifters out and
service them by cleaning and re-assembling if you find no broken bits. The
Bentley manual gives a good description of the process and it can be done
with the heads still on the engine. It's uncomfortable working from the
bottom of the engine but it's better than yanking the engine.

Regards,
Rick
84'GL camper wannabe "The Blue Brick"