These gear drive timing sets are specifically designed for LS engines used in racing, street, marine and extreme applications. They provide the most accurate valve timing possible by eliminating chain flutter and backlash. They bolt on without modification, maintaining the your current oil pump and timing cover on RHS® LS Race Blocks. Does not fit dry sump models (LS7, LS9, etc.). External oil pump required on dry sump applications. These are the world’s only gear drives for LS engines and are based on the award-winning COMP Cams® LS Sprint Car Gear Drive. LS Gear Drive Timing Sets are designed for three-bolt cams and work with all 24x and 58x LS engines.