Wilson Manifolds Tapered Spacers feature a computer generated variable radius taper design that maximizes the airflow through the carburetor and enhances air/fuel distribution for more horsepower. Part throttle performance and distribution are improved by redirecting the flow pattern created by the partially open throttle blades and gradually reducing the velocity of the air/fuel mixture entering the plenum to allow for a smoother transition into each runner; full throttle performance is improved by increased flow. Our Tapered spacers can increase flow through the carburetor/throttle body by as much as 110 CFM. Wilson Manifolds tapered spacers will increase torque, horsepower and acceleration throughout the entire RPM range. We offer the most complete line of 4-Hole Tapered spacers in 390, 4150, 4500, Q-Jet & 2bbl adapters to provide the high performance consumer with the ability to tune their engine for the maximum performance for any application. Wilson Manifolds is the only manufacturer to offer a choice of tapered spacer heights and produces the only fully CNC machined billet tapered spacer on the market. Wilson Manifolds Tapered spacers will benefit any vehicle that operates under both part and full throttle conditions such as bracket racing using a throttle stop, drag racing, circle track, road racing, off shore power boats, street/strip engines and towing vehicles. * Up To 30+ Bolt On Horsepower * Improves Throttle Response * Improves Distribution * Increases Signal To The Carburetor * Increases Flow Through The Carburetor / Throttle Body * Oval, Drag, Street, Marine & Towing * Works Through The Entire RPM Range * Light Weight Design * Over 30 Years Experience Making Tapered Spacers * Alcohol Compatible