Aluminum HP Main Body Retro-Fit Kit-850 CFM HP Main Body 850 Kit Converts 0-4781C, 0-4781S, 0-4781SA, 0-76850, & 0-76851 Double Pumpers to the 850 CFM HP Series Main Body HolleyWant to upgrade your street carburetor to a high performance race carb, but don't have the means to do a complete carb swap? If you can turn a screwdriver, you can get increased horse power from the new Holley Aluminum HP carburetor main bodies. These aluminum HP main body retrofit kits convert your existing 650, 750, or 850 cfm double pumper to an aluminum HP main body for increased horsepower, torque & airflow. With no air horn, choke tower, or