I'm sure Dominic drilled the holes for air to pass through there when filling the cooling system up instead of waiting for the thermostat to open to burp the air out of the cooling passages shruggy
I've never thought of blocking that passage in the water pump housings, what are the needs, reasons, to do that confused

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)