The groove in a valve stem, seemingly unimportant, in reality is vital to the success of a valves performance. Imperfectly formed grooves, inferior or mismatched locks, and improper retainers can lead to catastrophic failure. The so called "conventional" or square groove design has enjoyed enormous success. But the success of a "conventional" groove is dependent upon precise machining. First, the surface finish of the groove must be outstanding to guarantee against failure due to residual machining marks. Next, the groove must have a precise .013" radius in the upper corner. Too small a radius leaves the groove subject to the dangers of a sharp fillet. Too large a radius leaves open the possibility of the groove being abraded in this area by the upper inside edge of the tang of the lock. Also, an oversized radius leaves a reduced horizontal shelf in the groove which is, or should be, the only contact point with the tang of the lock. Contact by the lock in the root of the groove is a disaster waiting to happen. Perfectly formed "conventional" grooves with proper locks and retainers will deliver good service. However, there are sub-standard components on the market that can conspire to destroy a correctly machined groove. The essence of the bead Loc groove is its simplicity and forgiveness. The groove itself is a straightforward .110" full radius. The contact points with a bead Loc radius lock are approximately 2:00 and 10:00 oclock, not at the root of the groove. This system affords minimal vertical movement, especially when valve float is present, which means reduced erosion of the valve for enhanced service life. MANLEY performance supports both the "conventional" groove system and the bead Loc system with the most extensive line-up of the highest quality locks in the industry.