After setting hydraulic lifter preload, tighten the ______ locking Allen screw.

• A. Polylock
• B. Locknut
• C. Cam Screw
• D. Dowel Screw

Answer: (A)

After you’ve achieved the desired preload on the hydraulic lifter, you need a locking mechanism to prevent any movement from occurring once the engine is running. The tool designed for this is the polylock, which is a locking Allen screw that threads onto the adjuster screw. Tightening the polylock Allen screw clamps the adjuster in place, so vibrations, oil pressure, or temperature changes won’t alter the preload you just set.

A locknut is a more generic locking method and isn’t the standard locking device used with these adjustable lifter assemblies. Cam screws and dowel screws aren’t involved in locking lifter preload.