Hydraulic lifters eliminate the need for valve lash adjustments where there is a clearance between the rocker arm and the valve.. The pushrod seat in the center of the lifter body sits on a plunger and spring. The lifter body has a small hole that allows engine oil into it. When you adjust the lifters (at the rocker arms), the pushrod seat is pushed down into the lifter body a small distance. This results in a "zero lash" arrangement, in which there is no clearance between the rocker arm and valve; this allows the pushrod seat to move up or down in the lifter body to compensate for wear in the valve train. Generally, hydraulic lifters do not need adjustment but if you have disassembled the valve train for any reason, an initial adjustment is required.
Remove one valve cover.
Install oil deflectors in the pushrod end of the rocker arm. You can do the adjustment without them but they help keep oil splatter to a minimum. Place some shop rags along the lower edge of the cylinder head, above the exhaust manifold to help catch any oil buildup.
Start the engine. Working from the front to rear of the cylinder head, slowly loosen the adjusting nut in the center of the rocker arm until you hear it start to click, then slowly tighten the adjusting nut until the clicking stops. Continue to slowly tighten the adjusting nut an additional one full turn. Move to the next rocker arm and repeat.
Wipe up any oil with a shop rag and replace the valve cover. Remove the other valve cover and repeat the procedure.
