These Carburettors that are intended for use with superchargers, and have a unique capability that allows their power Valves to reference the intake Manifold vacuum below the supercharger. This allows the power valve to operate as it should, based off intake Manifold vacuum. A power valve provides further enrichment to the main metering system under load (low vacuum) conditions. Without this external referencing, the power valve would be "reading" the Supercharger boost pressure, which has no bearing on the engine load.

• Model 4150 with shiny finish
• Small block Chevrolet 1x4, 170 series blower calibration
• Four-corner idle system
• Manual choke
• Dual 50cc accelerator pumps
• Mechanical secondary
• Boost referenced power valve