1736 1971-1974 232 258 AMC IHC Scout 4-1/2" water pumpThe 1736 pump has an impeller with an increased vane count and a reduced impeller vane clearance. It achieves greater flow rates, higher head pressure and a more efficient flow. The impeller color is due to Type II Class II military grade surface coating which protects against corrosive fluids. FlowKooler introduced the first hi flow pumps and continues to improve impeller design. Why is increased flow so important to cooling a hot 258 engine? Because