It has hydraulic roller lifters.
solid lifters at a 012-inch clearance
The hydraulic lifters do not require adjustment nearly as often as solid lifters.
Hydraulic lifters would be STOCK from the factory. On the 84 engine.
Yes it does. Chevy did not use solid lifters in that engine.
Assuming solid lifters (as opposed to hydraulic, self-adjusting lifters) you could burn valves if the lifters are adjusted too tight or have excessive valve clatter if the lifters are adjusted too loose.
YES, Unless someone has installed a solid lift cam sometime are another.
You could take off a rocker and try to push down on the pushrod. You'd be able to feel the spring in a hydraulic lifter, but not on a solid lifter.
It has hydraulic lifters that are known to get noisy. Mazda sells a shim set that can be installed under each lifter to reduce clearance so that the lifters don't require as much pump-up travel. The lifters are located in the ends of the rocker arms, replacing or shimming them requires the removal of part of the intake plenum. You can also buy new lifters in the aftermarket for about $20. each, but there is 12 so it's not exactly cheap.
I guess that you are talking about a hydraulic lifter for an auto engine. There is no repair for these. They can be converted to "solid" lifters or used as paper weights.
I was taught it was a noise thing - less noise in the hydraulic system due to less tapping of metal on metal. Hope someone reads this and verifies, but that's what I was taught.
It has nothing to do with the lifters getting use to your driving style. Lifters rarely loosen up. Lifters wear over time, thus causing the gap to widen, creating lifter clatter. On solid lifters, that is why they must be adjusted periodically. On hydraulic lifters, this is not necessary, as they automatically adjust for the gap due to wear, if they were installed and adjusted correctly in the first place.