Made specifically for racing applications using short or Corvette water pumps. Pulleys work with Sweet style power steering pump and pulley to provide the CORRECT ratio, ensuring that the power steering pump and the water pump operate within the RPM range specified by General Motors. Stock pulley ratios do not provide the correct ratio for use in racing where the engine RPM differs greatly from street applications. In order to provide 30% water pump speed, and reduce weight and inertia, the crankshaft and water pump pulleys are smaller in diameter than standard reduction pulleys. The acceleration capabilities of the engine are greatly enhanced. ALL31030 is 4-3/4" diameter. ALL31040 has 5/8" hole, 6-5/8" diameter. ALL31050 has 3/4"hole, 6-5/8" diameter.