^^^ good setup. As far I can tell also the orifice dimensions come from the aviation world. IMO the "spec." is not very exact but probably good enough. One might think a chart or table of flowrate and delta pressure exists somewhere but as mentioned what they have now is good enough.

The spec for the orifice size is in the FAA regs.

"For an engine cylinder having less than a 5.00-inch bore; 0.040-inch orifice diameter; .250 inch long; and a 60-degree approach angle."

The approach angle and length are critical for comparisons between two different leakdown testers.

To close this out. Buyers never asked about a compression test after seeing the leak-down test. So I didn't retest with a hot or warm motor. Car sold. Issue is resolved.