Using state-of-the-art racing technology, Edelbrock has designed these "super cooling" aluminum water pumps to provide maximum flow, maximum pressure and equal distribution to both sides of the block within 1%. On the racetrack, Edelbrock aluminum pumps have been accepted by racers in all divisions from street stock to NASCAR Cup. This endorsement by racers is the ultimate proof of the superiority of Edelbrock's Victor Series Aluminum Water Pumps. Independent testing by Ed Pink proved that the Edelbrock water pumps flow more coolant through the engine than our competitors. The Edelbrock pump generated 11. 8 gallons per minute more flow than the leading pump with a similar design. All other pumps were unequal in distribution, one brand as much as 2 gallons per minute per side. The Edelbrock pump achieves equal distribution within 1/10th of a gallon. According to Ed Pink, "This pump flows more water through the entire engine and radiator system. The equal water flow and pressure on both sides of the engine is an outstanding achievement. " All water pumps were flow tested at the same speed using laboratory-type, in-line turbine flow meters. Pump speed was 5/8 engine speed. Dimension from block surface to hub: 5-5/8". Fits all 1955-68 small-block Chevy passenger cars, 1969-70 350 c. i. d. Corvettes and 1955-72 light duty trucks. Has 3/4" ball/ball bearing.Pit Stop USA offers Edelbrock Victor Aluminum Water Pump - SB Chevy - Standard Rotation - Long-Style Pump - 5/8" Pilot Shaft 8811 at low everyday prices. Be sure to check out all of our products from Edelbrock including Edelbrock Small Block Chevy Water Pumps.