Originally Posted By Jopar
One more... my theory is the pump generates so much pressure that it was fighting control with the thermostat.


Another theory to toss around; '68-earlier BB water pump housings are different for A/C and non-A/C installations. I believe the cavity behind the water pump is the difference and might be at the core of some temperature-related problems. IOW, pump vane/housing incompatibility.

Since the casting numbers of both appear to be the same, I don't know how to compare the two.

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