COMP Cams Valve Locks 5/16in Single Groove

In this set, you get 16 pairs of hardened steel street valve locks. Each lock is designed with a single groove, a 7-degree angle, and fits a 5/16-inch valve stem. These are intended as a direct replacement for stock engine rebuilds, especially for street applications where valve spring loads aren't excessively high.

It's really important that your valve locks match your valve size precisely. When installed correctly, there should be a small gap between the two halves of the lock. If they butt together without a gap, they're too big. If they fit loosely on the stem, leaving a gap in the middle, they're too small. The tang on the lock's inside isn't what holds everything together under high spring pressure; that's the job of the retainer's taper. The tang just helps position the parts until the retainer's taper creates a secure 'collet' effect, binding the lock and retainer together. The harder the spring pushes, the tighter this connection becomes.