What is a poly lock, and how is it used?
Essentially, a poly lock is an adjustable rocker arm nut used with stud mount rocker arms.
Each poly lock features a threaded body and a set screw. The body screws over the stud and is designed to hold the rocker arm in place. Then, the set screw is tightened down against the stud, locking the body in place.
The greatest advantage of poly locks is that they make adjusting you valvetrain much easier. Not only are they useful when setting preload on hydraulic lifters, but they are required to set valve lash on solid lifters.
Polylock can be adjusted by following the steps below:
- Set the valve lash or lifter preload by turning the outer hex nut.
- Loosen the outer hex nut approximately 1/16 turn.
- Tighten the set screw.
- Tighten both the screw and nut together until they become much harder to turn (25-30 ft.-lbs).
The outer hex nut should be back in the same place it was before you loosened it. If your lash setting is off, loosen up the poly lock and try again.