The vacuum levels don't have anything to do with the bleeding of the
brakes, I assume you just happened to run across that spec.
22 is just fine. It just effects how much pedal force you must apply.ie,
Remember that the car runs at various throttle positions so the vacuum
avail changes during operation on an ICE more than on an electric. The
usually keep enough in the body of the brake booster with a check valve
for one good stop if the engine dies. They also have to design with the
variety of drivers out there. I assume you are not a 95 lb octogenarian?
(no offense intended if you are)
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