Badly out of adjustment hydraulic lifters will not pump oil through the pushrods. Sometimes it will take a couple of minutes of running to get a steady flow of oil through the pushrods. Be sure the valves are fully closed on each cylinder, then loosen the rocker arm nuts, let the lifters top out, take out the slack with the adjusting nut and continue to turn the nut 3/4-1 turn past the zero-clearance point. Repeat for all 16 valves, one compression stroke at a time.
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!