That engine most likely has hydraulic lifters. Loose rockers indicate something is stuck, (like valve stems in the guides) or the rockers are way out of adjustment. Even with both valves fully closed, there shouldn't be any looseness between the rockers and the valve stems.
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!
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