Radiator question

An old radiator guy showed me a quick test for flow on the radiator. When cool, remove lower hose. Put hand over bottom outlet. Fill with water. Pull hand off outlet quickly. If water comes out fast, there's no major blockage. Comes out lazy, there's an issue. My Dart was running hot. New aluminum radiator. I put 1/8 inch holes in the thermostat. Installed a spring in the bottom hose. Made a fan shroud. Runs cool at all times. Do you have a shroud?