Vacuum questions


1984ranger28

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Is 17 Hg of vacuum a healthy engine? The needle is very steady. Thanks, Lucas.
 


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RonD

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If you are under 2,000ft elevation then its barely OK
18" to 22" is expected, but the scale drops by 1" per 1,000ft elevation

So in Denver, 17" would be the top end of the scale, 5,000ft 13-17" expected

In 1984 models, spark timing was set manually so may need adjusting

If engine has 250k or more miles, the running compression will be lower so lower vacuum

But 17" steady means engine is still running OK

Many other tests you can do with vacuum gauge that can tell you if its low for a reason read here: http://www.gregsengine.com/using-a-vacuum-gauge.html


Also, grain of salt, vacuum gauges are not calibrated that often :)
You can test gauge on another engine to see what it says
 
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1984ranger28

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Thanks for the help Ron. It was a while since I adjusted the carb, so I did that, and got the vacuum up to 20 Hg and did the test where you opened and closed the throttle, and checked out perfect.
 

RonD

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Good work :icon_thumby:

20" is much much better
 


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