Wilson Manifolds' Carburetor Spacers have been used by more pole, race, and championship winning teams than any other brand in the world. Our Spacers have been developed through years of testing with the top race teams in nearly all forms of motorsports. Wilson Manifolds offers the largest selection of spacer designs and heights in the industry. This assures that we have a spacer design for virtually all classes of racing that will provide optimum power and distribution. Our precision machining centers allow us to produce the lightest spacer available while still maintaining a high level of structural integrity. This design also reduces the cross-sectional area available for conduction heat transfer from the intake manifold to the carburetor. All Wilson Manifolds spacers, including our tapered spacers, are CNC machined from billet 6061 aluminum for strength, light weight, quality and durability. After machining, a military specification hard coat is applied to each spacer that will not wear off, is scratch resistant, is not affected by alcohol and eliminates corrosion. Wilson Manifolds open spacers have become the standard in NASCAR Cup racing, but are for use in any application where a top quality light-weight billet spacer is desired. Open spacers increase plenum volume and move the throttle blades away from the roof of the runners, allowing the air/fuel mixture to turn more easily into the runners for improved distribution and mixture quality. Open spacers will add mid range and top end hp. Wilson Manifolds is the only manufacturer to produce open spacers in thicknesses from 1" to 2" in 1/8" increments for 4150 carburetors for precise tuning and for applications where hood clearance is at a premium. The engine builder spacer kit includes all nine open spacers (4150) in 1/8" increments and is a must have for any dyno room and for track tuning. Adds mid & top end powerIncrease plenum volumeAllows the air/fuel mixture to turn more easily into the runners by moving the carburetor up away from therunner rooflineImproved distribution and mixture qualityWill add mid range and top end hp1" to 2" Heights in 1/8" increments for 4150 carburetorsWilson Manifolds is the only manufacturer that offers multiple heights for 4500 carburetors4150 spacers are designed to pass NASCAR No-Go GaugesPit Stop USA offers Wilson Manifolds Open Carburetor Spacer - Holley 4150 Series - 1.5" Tall 30 at low everyday prices. Be sure to check out all of our products from Wilson Manifolds including Wilson Manifolds Carburetor Spacers.