Proper procedure for engine running adjustment...
Remove valve cover bank 1-3-5-7. Turn engine over (by hand is preferred), until both Exhaust and Intake on number 1 are closed. Loosen nuts on both #1 Int and Ext rockers until both push rods are loose.
Hold #1 forward push rod between fingers and rotate and move up and down. Start tightening rocker nut until push rod will no longer move up and down. Spin push rod with fingers it should still spin. Turn nut 1/2 turn. Push rod might still spin but will have noticable resistance. Repeat for next push rod in line. Now you are done with the #1 cylinder rockers.
Notice the amount of exposed thread on the stud. From the top of the nut to the top of the stud the distance should be about 3/16 or a little more. Rake your thumbnail over the exposed stud and note 3 to 5 threads. The one next to it should look and feel the same. Now make all the rest in line to look the same.
Start the engine and start at one end and work toward the other. A piece of card stock or corrugated box is good to help control the oil that comes up. Loosen the first rocker nut until it starts to tap, then tighten to just when the tapping stops. Turn nut clockwise additional 1/2 turn and then do the next one and all the rest in sequence. Shut down the engine. Now all the lifters on the bank are pre-loaded.
Take a straight edge across the tops of all the rocker studs. Any that are sticking up higher than the others are starting to pull out of the head. Notice where the nuts ended up. All should be online and consistent. Any that are lower than the others have a; bent push rod, collapsed lifter, is a flat lobe or has other issues.
Now you can clean area, replace valve cover and do the other side.
After this is done all lifters have correct preload and there should be no ticking.
Make notes of what you find while doing this, and correct mechanical damage as necessary.