interstate driving = overheating?

[73ta]

Pontiac water pumps come in two styles, one with cast vanes and one with sheetmetal vanes. Cast is reported to be better. There is a devider plate sandwiched between the two gaskets. Because of the differences on rebuilt and new pumps the clearance between the pump vanes and the plate vary wildly. Mine had almot a 1/4" clearance. The plate needs to be massaged down to leave a smaller clearance, set mine at about 0.040". This will increase water flow, reducing temp. There is a huge thread on the PY board about it and Pontiac overheating problems.