GWP187 - A/A+ Water Pump – Large Cast Impeller (No Bypass)
Using a high capacity water pump helps to reduce cavitation in the water jackets at higher RPM.
This higher capacity water pump with larger impeller moves more coolant than the small impeller GWP132 (850/997 Blocks) This pump does not have a bypass. The impeller protrudes into the block slightly more than 1/2″ and fits all 1275 Blocks and most 998/1098 blocks from 1967.
Further reduction of cavitation is achieved by using a large diameter water pump pulley, If using a larger pulley it is necessary to check clearance between the large pulley and the head.