Wilson Manifolds builds several styles of lightweight billet aluminum carb spacers, but they are most well known (especially in NASCAR circles) for their open spacers that increase plenum volume and move the throttle blades away from the roof of the manifold runners. This allows the air/fuel mixture to turn more easily into the runners for improved distribution and flow. Open spacers typically add power to the mid range and top end of the power band.

Wilson Manifolds is the only manufacturer to offer open spacers for 4150-style carburetors in 1/8" increments from one to two inches. These precise incremental steps in spacer thickness allow for more precise tuning and are necessary for vehicles where hood clearance is critical. All Wilson spacers are CNC-machined out of 6061 aluminum for weight savings, strength and durability. A scratch resistant Mil-Spec hard coat is applied to resist corrosion, even against alcohol fuels.

Wilson?s open carb spacers are available as a 9-piece engine builder?s kit or individually. They are designed to pass NASCAR "No-Go" gauges and specific spacers are NASCAR legal. Also available is a 1.50" 4500 to 4150 adapter and a 1.00"-thick Open Quadrajet Spreadbore spacer.