Holley Pro-Series HP Carburetors set the standards by which all competition carbs are judged. Built only for all-out performance, Pro-Series 4150 Carburetors perform like the more expensive "modified" carburetors at a considerably lower cost. To greatly improve air flow, airhorn and choke towers have been removed, venturi sections have been modified, and the through-holes have been machined to . 440". Improved main metering circuitry. Pro Series carbs have been fit with 4500 Dominator fuel bowls, high flow power valves, and accelerator pumps equipped with severe usage diaphrams. This four barrel carburetor flows 830 cfm and is hand-built by Holley technicians. Wet flow tested from idle to full throttle in simulated racing conditions. Features fully-contoured main body, redesigned metering blocks, and high flow needle and seat assemblies. NASCAR approved.Pit Stop USA offers Holley Pro Series Carburetor - 390 CFM Four Barrel - Model 4150 HP 0-80507-1 at low everyday prices. Be sure to check out all of our products from Holley Performance Products including Holley Performance Products 390 CFM Gasoline Carbs.