The Edelbrock Performer Square Bore Air Valve Secondary Manual Choke New Carburetor features a two-piece, all-aluminum construction for cooler operating temperatures and less warping. It is designed and calibrated for good street performance and fuel economy in 402 CID and larger engines with the Edelbrock Performer manifolds. There are no gaskets below the fuel bowl level for fewer leaks and no plastic parts or power valves to blow out. The Performer manual choke carburetor includes both timed and full vacuum ports for ignition advance. The carburetors use easily changed metering rods for precise tuning. The Edelbrock Performer covers the replacement or repair of the product only and does not cover the cost of removal and installation.Bore Diameter :Primary Bore 1.44; Secondary Bore 1.69