Edelbrock #8817 Water Pump SBC Competition 3/8 npt outlet holes designed for circle track and endurance racing applications, they feature a revised impeller entry, a hard black anodized finish and .100" thicker rear cover for greater durability. Auxiliary water outlets ease fabrication of custom plumbing systems and auxiliary fittings are available as an or npt. These Water Pumps provide maximum cooling with equal distribution to both sides of the block within 1%. By eliminating hot spots, the engine produces optimum power from every cylinder without detonation and pre-ignition. Other features include billet steel hub and heavy-duty ball/roller bearings.