Edelbrock Ford 351 W Dual Quad Air Gap ManifoldEdelbrock part #7585 RPM Air Gap Dual Quad 351W intake manifold is designed for 351W small block Fords. This intake offers performance improvements in the 1500 6500 rpm range. The large runners feature our unique Air Gap design that separates the runners from the hot engine valley for a cooler, denser charge and more horsepower. Includes bosses for rear water crossover. Carb center to carb center is 6 7 16". Use Progressive Throttle Linkage Kit