Whenever you change valvesprings, there are a number of things to check. The inside of the valvesprings need to be positively located on the head; COMP Cams offers a variety of inside diameter spring seats to fit around the valveguides on the head and properly locate the springs. If you're changing the outside diameter of the spring, you'll need to change retainers too. Even if you're not, always inspect every retainer and valve lock (also called a valve keeper) for damage or wear. A failure here means a dropped valve and severe engine damage.