Air Cairo Receives its 1st Airbus A320neo Billet Aluminum Water Pump Fan Pulley 240Z 260Z 280Z 280ZX. New billet aluminum water pump pulley for Datsun 240Z 260Z 280Z and 280ZX. Pulley is available with two different belt widths which we will call thinner and thicker, basically 3 8" wide or 1 2" wide belts. The idea is to get all of your pulleys to have matching belt widths for best performance. Thinner pulley groove= . 380" at the top of the "V". uses 3 8" or 10mm wide belts. Thicker pulley groove= . 440" at the top of the "V", uses up to 1 2" wide belts. Most of the new balancers and alternators are using the thinner (3 8") belt. *Pulleys include a thin spacer as we have found that the pulley might rub on some brands of water pumps.