Rick,
Here's K&N's procedure. Most of it describes the calibration of the SuperFlow bench, but they do discuss diameters and radiused inlets and all that stuff.
http://www.knfilters.com/testmethod.htm
One thing of note, they are flowing at a very low pressure, or 1.5 inches of water. What I plan on doing--haven't done yet--is flow a 4 Bbl carb without a filter, then flow the Stelling & Hellings followed by the K&N. Guess I'd better get busy. While I'm at it, I should test a big-diameter filter with the latest housing just to make me feel bad about what I'm running. At least I have 2X4 Bbl setup.
One thing is for sure: To maintain some originality, airflow is sacrifice. There are much better filter setups that the Stellings & Hellings, what with more area, shaped bases, an cold-air ducting. But I'm just trying to maintain the original "old tech" look, but with more filtering capability and, hopefully, some improved airflow. But for a serious show, the foam Stellings & Hellings goes back on.
