The Wilson spacer controls these harmonics by isolating the carburetor from the engine vibration allowing for a more consistent and less aerated amount of fuel to be delivered to the engine. The spacers feature a vibration resistant composite construction in both the upper and lower flanges, which can reduce harmful harmonics buy as much as 50%. We found a two inch thick Wilson tapered spacer for a 4150 carb for $188.95. Contact Wilson Manifolds at (954) 771-6216 www.wilsonmanifolds.com