WATER PUMP LARGE CAST IMPELLOR

Large impeller higher capacity water pump This moved more coolant than the original early GWP132 standard pumps, and is better quality. GWP134 has by-pass hose take off, GWP187 is without take off. These super high quality water pumps have a much the larger impeller; it sticks into the block slightly more than 1/2" (14.03mm). The impeller in these aluminum bodied pumps is long lasting cast iron, not stamped steel as in many aftermarket pumps. This water pump will fit all 1275cc blocks, and all small bore blocks, with the excpetion of early 850/997cc units.These will need an amount of modification-relieving corrosion and slight material from the liner wall and impeller if required should enable clearance,try spinning pump loosely fitted without gasket for clearance. The hi capacity water pump helps to reduce cavitation in the water jacket, particularly at high RPM, as well as circulating a greater volume of coolant. Further reduction of cavitation is achieved by using a large diameter water pump pulley CAM6408 as originally fitted to the Cooper S and reintroduced on the A-Plus engines. It is necessary to check clearance between the large pulley and the head; if a lot of material has been machined from the head face it may foul the pulley. Small bore engines with 12G940 heads can't use CAM6408 and it is necessary to modify the top edge of the high capacity water pump or the 12G940 head will rest on the pump and not seal properly; modify for at least 1/16" gap.