Hydraulic lifters are made of a hardened shell case that is partially hollow in the middle. The inside of a standard hydraulic lifter encompasses an open cavity with a pushrod, a plunger seat, and a lightweight plunger spring. The engine's oil pump transfers the fluid through the lifter valley, where it's then directed into the lifters to create a hydraulic plunger. With this type of design the lifters can safely compensate for valvetrain harmonics. Solid-lifter designs require the use a feeler gauge to create a camshaft manufacturer-predetermined lash gap between the rocker and the valve tip.
Method 1
Hydraulic Lifter With Stock
Locking Rocker Nut
This type of lifter and rocker-nut combination requires the engine builder to turn the rocker nut 31/44-turn once the rocker and pushrod meet. This places a bit of load on the lifter's internal plunger and creates a smaller lifter cavity to make it easier for the oil pressure to provide a cushion for valvetrain lash.
Powerhouse 51/48-inch E-Z...
Powerhouse 51/48-inch E-Z Valve Lash Wrench with 31/416-inch and 71/432-inch T-handles
Method 2
Hydraulic Lifter With Two-Piece Locking Nut
The same theory holds true here, the only difference being the type of rocker nut and the method by which it is turned. In this case the rocker and pushrod meet just before the outer rocker nut is turned 11/42-turn. This places 21/43 the amount of lash on the hydraulic lifter's internal plunger. From there the internal rocker nut should be run down until it bottoms out. At this point the internal rocker nut needs to be held tight as the outer rocker nut is rotated an additional 11/44-turn. The internal lock nut will then secure itself against the external rocker nut to hold the proper rocker-arm load.
Method 3
Solid Lifter
Solid-lifter applications require a feeler gauge to set a manufacturer's predetermined amount of lash. As the rocker nut places the rocker against the pushrod, the feeler gauge is pushed in between the valve tip and the rocker. This gap is the amount of lash the valvetrain is allowed. At this point either rocker-nut assembly mentioned earlier can be fastened to hold the proper amount of gap by allowing the feeler gauge to snuggly slip in and out of the gap between the rocker and valve tip.
We set the lash on our solid lifter-equipped engine using the two-piece locking nut design. The No. 1 cylinder led us off as we worked a cylinder at a time through all eight holes in a matter of minutes. Then we reinstalled the valve covers, fired up the engine, and listened for any rattling or snapping. It's important to note that a poor idle can also be the result of improperly lashed valves. Don't get discouraged if you don't get it right on your first attempt-just get under the hood and try again.