[57taskforce]

Pull the valve covers off and push down on all the rockers one at a time when the rockers are relaxed(tdc on each cylinder). If it’s a collapsed or not primed lifter you should be able to tell which one it is. Might be as simple as a rocker or two that are backed off. You can take a dead blow hammer or rubber mallet and smack the valves one at time when the rockers are relaxed and check to see how free the valves move. I would bet it’s a lifter not priming up or a rocker nut that is backed off/rocker stud that is loose or pulled.