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Old 05-11-2004, 07:39 PM
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vacuum gauge

i can get a deal on a autometer vacuum gauge that matches the rest of my guages, but what is the purpose of having one, is it a useful gauge to have?

thanks very much

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Old 05-11-2004, 08:57 PM
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I have one in my truck that I use in conjuction with a A/F ratio meter that I use for testing my carb setup and tuning the power valve.

For normal daily use there really is no reason to have one.

Some use it to aid in better mileage by keeping the vacuum as high as they can while driving and that means the throttle isn't open as much, hence the better mileage.
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Old 05-11-2004, 09:08 PM
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hmmm, so it would make a good tuning device? i want to tune my car perfectly, i just dont know if i need a permanent guage, but if u say i can use it to get some fuel economy it might be worth it.
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Old 05-11-2004, 09:14 PM
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To be honest I tried driving by the vacuum reading for awhile to see if it actually made a difference and it does but it is like driving with a egg under the throttle pedal. Very light changes and no stomping on the pedal.

Sorta took the fun out of driving.

But they are a good tuning aid when used with other tools.
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Old 05-11-2004, 11:03 PM
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does it just run off intake vacuum? or can it go to other things?
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Old 05-12-2004, 07:11 AM
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Any FULL manifold vacuum port will be fine.
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Old 05-12-2004, 09:11 AM
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The problem with using the Autometer vacuum gauge (or any other vacuum gauge that is designed to be permanetly mounted inside the car), is the fact that they are usually "dampened" gauges. They are dampened so that the needle doesn't fluctuate rapidly and they only give an "average" vacuum report.
The vacuum gauges that are designed as tuning tools are hand-held, or can be hung under the hood. These gauges show the actual fluctuations in vacuum, which is necessaey for tuning.
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Old 05-12-2004, 10:37 AM
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engineguy

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they only give an "average" vacuum report
Hmmm both my hand held gauge and my in compartment gauge show the same reading.
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Old 05-12-2004, 11:53 AM
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Yes, both gauges will read basically the same vaccum. The dampened gauge will not show the rapid movement of the needle, which is necessary for accurately tuning and/or trouble shooting. The dampened gauge will not have the quickness, nor the range of individual fluctuations, but the overall vacuum reading will be very close to the tuning gauge. In just about all situations where a vacuum gauge is used for tuning, the difference between the minimum and maximum vacuum for each cylinder is very critical. A dampened vacuum gauge just will not show the detail needed for optimum diagnosis.
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Old 05-12-2004, 12:19 PM
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but you can use a dampened guage to get optimal fuel economy?
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Old 05-12-2004, 07:11 PM
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i didn't realize that they were dampened. it might not be as useful as i thought, how much fuel economy do u actually save driving at the highest vacuum?
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Old 05-12-2004, 07:15 PM
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Vacuum guages where put in cars in the 60s, so that you can get optimum gas mileage. I theory, the higher that you keep the vacuum while driving, the better the mileage that you get.

A pretty good item to have with todays gas prices.........
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Old 05-13-2004, 05:01 PM
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You can still tune your carb with a vacuum gauge that is dampened as you are trying to attain the highest vacuum reading when setting the mixture screws.
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Old 05-13-2004, 05:29 PM
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Having a vacuum gauge inside the vehicle is next to useless if you ask me. Sure it will show you when your getting the best fuel economy, but if you have ever had one you can attest that happens when your foot is the farthest from the floor. Save the vacuum gauge for tuning, having a needle swinging wildly in front of your face every time you touch the accelerator will just become annoying...trust me. As far as I know I have never seen a dampened vacuum gauge designed to mount inside the car, they are all undampened. If you want to dampen an existing one you can use a "snubber" on the port in the manifold.
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Old 05-13-2004, 07:10 PM
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this is the gauge.

they have very limited info on it.
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