1647 early 1969 Pontiac 4" "11 Bolt" water pump

This is the elusive 1969 only "short" pump.  Classic Pontiacs run hot so Flowkooler designed a high flow 11 bolt pump with a CNC machined billet impeller. With increased vane count and a reduced plate-to-impeller vane clearance it achieves higher 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 Pontiac  engine? Because it has been proven time and time again that reducing the cycle time between the heat source and the heat sink creates more opportunities to shed heat and drop engine temperatures.

From 0-3,300 RPM…Nothing Beats a FlowKooler!

Reducing the gap between the backing plate and the impeller

Pontiac owners have reported that (1) heat cycling may result in a distortion the backing plate and (2) coolant degradation may corrode the backing plate necessitating replacement.  Some cooling gains may be experienced by reducing the backing plate-to-impeller vane clearance. In closing the impeller-to-plate gap pressure is built, efficiency is achieved and more coolant will route to the thermostat and radiator which initiates the engine cooling process.  Please note that inadequate clearance that results in an impeller vane to backing plate interference will cause friction.  Any owner modifications to the Pontiac part design are performed at the owner's discretion and FAILURE TO MAINTAIN ADEQUATE CLEARANCE WILL VOID WARRANTY.

*Note: This pump is for the 1969 400 blocks with casting #9796351.  The 1969 400 pump measures 4".  The 4-1/2" taller more common pump is 1649.