Here is a Detailed Cutaway Photograph in Blu-Ray High Definition that I found on the web showing you what the lifter does and why it's adjusted like it is.
Intake Valve fully closed, exhaust Valve beginning to open. {adj. Intake}
Exhaust valve fully closed intake valve Beginning to open. {adj. Exhaust}
First, see the multi angle cutaway below.
If you turn the nut down until the pushrod stops being able to be twisted, you can put a heavy bind on the spring (not pictured) and if you're tough enough, you can actually still twist it until the lifter is fully collapsed.
THIS IS WHAT YOU DO NOT WANT.
The reason you only go 3/4 of a turn and NO FARTHER, is to prevent the bottoming out of the plunger thus loosing any cushion the oil gives you.
So, when adjusting your hydraulic lifters, you tighten the rocker nut until it TOUCHES the lifter plunger. From that point you only need to take it a few thousandths of an inch farther into the hole as it's then well within the area where the oil pressure will keep everything in specs. (unless the lifter looses it's integrity)
The ACTUAL amount of turn to give ANY hydraulic Rocker Nut all depends on the threads on the rocker stud. The twist rate is what determines the distance traveled into the plunger spring.
You only need a few thousandths of an inch travel into the plunger to be perfectly adjusted. All it does is REMOVE slack between the pushrod and the rocker, which in turn, removes slack between the rocker and the Valve stem, which in turn removes the TAPPING noise from the engine, which in turn.... Makes everyone happy
After some indeterminate # of miles, you will likely experience a little noise at startup or on cold mornings when the oil has drained back a little from loss of tolerances in the lifter bores etc... This is normal.
Quai Long DONG has spoken, you may go in peace.
Today
