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Old 12-27-2020, 06:47 PM   #1
msg
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Adding a vacuum gauge on a 66- where to connect on the manifold or carb?

I added a vacuum gauge to the instrument panel on my 66 and wondered where its best to run the hose. Is there a spot on the quadrajet that is best or should it be on the manifold?
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Old 12-27-2020, 07:27 PM   #2
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Re: Adding a vacuum gauge on a 66- where to connect on the manifold or carb?

If you want a correct reading you need to connect to manifold vacuum. Generally speaking, the upper ports on the Quadrajet are ported and the lower ports are manifold vacuum. An easy way to tell is to hook up your vacuum gauge and observe it at idle. If it has little or no vacuum you're connected to a ported vacuum source.

Personally, my feeling is that you'll get more accurate information if you connect to the port on the manifold itself behind the carburetor.
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Old 12-27-2020, 08:17 PM   #3
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Re: Adding a vacuum gauge on a 66- where to connect on the manifold or carb?

https://cimg3.ibsrv.net/gimg/classic...f8a38dc7e8.jpg
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Old 12-27-2020, 11:40 PM   #4
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Re: Adding a vacuum gauge on a 66- where to connect on the manifold or carb?

Quote:
Originally Posted by truckster View Post
If you want a correct reading you need to connect to manifold vacuum. Generally speaking, the upper ports on the Quadrajet are ported and the lower ports are manifold vacuum. An easy way to tell is to hook up your vacuum gauge and observe it at idle. If it has little or no vacuum you're connected to a ported vacuum source.

Personally, my feeling is that you'll get more accurate information if you connect to the port on the manifold itself behind the carburetor.
Thanks Truckster, I was thinking to but I have a 2 port tee. Is it ok to splice the 1/4 vacuum tube off that tee behind the carb and run the transmission and the vacuum gauge from that one spot?

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Thanks Vince, Ill attach a pic of how the carb was set up before I replaced the engine. For all I know it was set up incorrectly.
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Last edited by msg; 12-27-2020 at 11:49 PM.
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Old 12-28-2020, 10:54 AM   #5
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Re: Adding a vacuum gauge on a 66- where to connect on the manifold or carb?

I just took a look on the Internet to find that picture but my knowledge on this carb is very limited. By guess and by golly and with some help from members of this forum mine seems to run OK now.
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Old 12-28-2020, 03:59 PM   #6
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Re: Adding a vacuum gauge on a 66- where to connect on the manifold or carb?

You can put a T in the line and run the vacuum gauge from that. It will not reduce the vacuum signal on the other legs of the T.
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Old 12-28-2020, 04:36 PM   #7
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Re: Adding a vacuum gauge on a 66- where to connect on the manifold or carb?

Thanks Truckster, that's what I will plan to do then!
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