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Vacuum gauge reading

Posted: Fri Sep 22, 2017 11:04 am
by pinzinator
What would be considered a normal reading on a vacuum gauge when connected to the intake? How steady should the needle be on a good engine?

Re: Vacuum gauge reading

Posted: Fri Sep 22, 2017 2:48 pm
by rmel
Assuming your vacuum gauge is calibrated in Inches of Mercury, at idle 800 -- 1,000 RPM should be about -17 to -20 InHG.
MAP readings are going to be strongly dependent upon load and RPM (and leaks).