Hipo65
Yeah I'm "That Guy"
Not trying to hijack this thread,but yes dried compressed air. With the test hose disconnected I crank up the regulator until it's zero or SET on the opposite gauge. Then with whatever motor im testing thread in to plug hole (@TDC) then hook up test line & read the % in the gauge I had set to zero. When the gauge is at SET or zero (discontented from test hose) it only takes 25-27 psi to get the percentage gauge to read SET or zero of that makes any sense to you.
