Comp Cams Valve Stem Locks

Product images may differ from actual product appearance.

Most people believe that the tang inside a valve lock is what holds the valve spring retainer and spring in place while the engine is running, however tangs are not strong enough to withstand today's open spring loads of 1000+ pounds. The tang's sole purpose is to temporarily locate the lock, retainer, and spring relative to the valve until the taper of the retainer can nest around the outside surface of the lock. This creates the "collet effect" that binds the two together; the more spring force exerted on the retainer as the valve opens, the more force applied by the collet effect to keep the retainer and lock in place.

With the emergence of valve sizes other than 5/16", 11/32", and 3/8", it is important to make sure valve locks match valve size. There should always be a small gap between the two halves of the lock when they are properly positioned on the valve stem. If the two halves are in contact without a gap, the valve locks are for a bigger stem. If the locks fit tight to the stem and leave a gap between the middle of the lock and the stem's outer diameter, the locks are too small for the valves. All locks should be checked before final installation to ensure they're the correct size.