COMP Cams 623-16 Machined Steel Set of 16-7 Degree, 8mm, Single Groove Race Locks

These single groove Machined Steel Street Locks with 7 degree lock angle and 8mm valve stem size are perfect locks for GM Gen III/LS1/LS2/LS6 applications. It is critically important to make sure valve locks match the 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 fit together without a gap, they are too large. If the locks fit tight to the stem and leave a gap between the middle of the lock and the O.D. of the stem, the locks are too small. Most people believe that the tang inside a valve lock holds the retainer and valve spring in place while the engine is running. This is not the case. The cross-section of material in the tang is not strong enough to withstand open spring loads of 1000 pounds. or more. The sole purpose of the tang 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 a “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.