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 stock oil pump and timing cover for all LS-based engines except dry sump models. Designed for three-bolt cams and work with all 24x and 58x LS engines. Based on the award-winning COMP Cams LS Sprint Car Gear Drive, these are the worlds only gear drives for LS engines.