Electrical water pumps are common in auto racing.
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They can be controlled electronically to adjust the rate of coolant flow "even after engine shut down".
Plan on purchasing an extra motor. You can get a engine driven mechanical water pump just about anywhere. Try to find the replacement water pump electric motor at your local Auto Zone.
I considered putting an electrical water pump on my '33 Ford but gave up the idea. Most electrical water pump mgfs. say they pumps are for racing only.
Simple is usually more reliable.
