Makes sense, But doesn't the pump suck the water out of the heater core on a small block V8? You are right, the old heater core doesn't need any extra pressure.
1953 Chevrolet 3600 Fried Green T'mater (Vern) In the Stovebolt Gallery Caution: Political Statement Man who runs in front of car gets tired, man who runs behind car gets exhausted.