Hope you can stand another "compression test results" thread

Buy or build a leakdown tester. .040 orifice and an air pressure regulator. If you have a compression gauge that quick connects, you can usually use it. Remove the Schrader valve. Google it. Lots of info on the 'net about them

The Horrid Freight one does not use "convention" and in my opinion is a waste of time. I modified one to use the "standard" .040" orifice and 80-100psi