If you read this post about the ProMax heads and look at the flow chart it touches on the subject. It’s been ages since I had that set of heads in my hands but on every Edelbrock Head and copy Head the common wall tapers in funneling the airflow at a high speed towards the valve while trying to make a sharp turn. Image going down a straight road at 100mph and speeding up to 120 going into the turn. Not gonna happen. The high speed air then jumps the valve opening and crashes into the good air going across the top of the port. A good head porter can hear this happening on a flowbench and knows the numbers are going to stall or back up. Control the speed with volume and angles and reap the benefits
https://board.moparts.org/ubbthread...l/small-block-mopar-promaxx-head-testing.html
