OEM magnum lifters setup

Is it normal for the stock OEM magnum lifters to bleed down at rest? I did not start the engine yet, just primed it with a drill. It takes up the lash with oil pressure but after 2 minutes the stock pedestal rockers are loose. I checked no.1 intake valve it takes almost half a turn to get the pushrod to stop turning. I had to go fast before the lifter bleeds down. I guess I need an assistant to prime the oil with I check all lifter preload....

engine is a 360 magnum, RHS magnum heads with stock rockers, pushrods and lifters.