Edelbrock Part # 5409 Performer RPM Dual-Quad intake manifold is designed to fit 1958-1965 Chevrolet 348/409 "W" big-block engines with factory large port or with our Performer RPM W-series heads #60809 or #60819. The manifold deliver performance with Edelbrock Performer Series or Thunder Series AVS dual-quad carburetors, and they accept our dual-quad fuel lines, throttle linkage, and air cleaners. Includes Oil Fill Tube (not installed) and matching push-in Breather. Oil Fill Tube and Breather are also available separately as #4803. Carb center-to-center measurement is 6-7/16".