How long does the engine need to sit before the lifters start to clatter on startup? A good hydraulic lifter should stay pumped up for a week or so without having to refill itself on the first start. Every time the engine stops, at least a few of the valves will be open, with valve spring pressure exerted on the lifter. It will slowly leak down- - - -nothing wrong with that, because otherwise the lifter could top out and hold the valve open the next time the engine starts. The problems start when the collapsed lifter takes a few seconds to refill. Other than being annoying, the noise isn't serious- - - - -UNLESS it goes on for a minute or so. A few clicks on a cold start after sitting idle for a day or more don't cause a problem. If it's taking several minutes to quiet down, you've got problems with either the check valves in the lifters, or very low oil pressure.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!