1972 mustang vacuum port question

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Cruz72

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I have a 1972 mustang with a 351 2v I’m trying to fine tune my carburetor but can’t find and information online and my tech manuals on which port is the intake manifold port that you are suppose to use while tuning carb with vacuum gauge if any one could provide a detailed picture would be much appreciated thanks 

 
I have a 1972 mustang with a 351 2v I’m trying to fine tune my carburetor but can’t find and information online and my tech manuals on which port is the intake manifold port that you are suppose to use while tuning carb with vacuum gauge if any one could provide a detailed picture would be much appreciated thanks 
In the rear of the intake manifold, behind the carb, you have the so called "vacuum tree". This is a source of direct manifold vacuum which have to be used for this application. For example your brake booster is connected to this. Generally this vacuum tree has multiple outlets and often one is unused but capped. Remove but keep this cap and connect your vacuum gauge. 

 
Yes I think I know exactly where that is only think I’m confused about is my tree has one line connected to two ports so tied into its self and one to the brakes if that makes any sense I’ll take a pic when I get home and post but this helps a lot thanks 

 
My guess is that one of the caps failed or one of the vacuum lines was removed and rather than go buy some new caps they just looped a piece of hose to cap two ports. Make sure you're not missing a vacuum line to something, like vacuum modulator on an automatic transmission, or vacuum to the control for air conditioning, or to the vacuum advance on the distributor, or to the EGR if you have it and your DMV requires it to be operational.

 
Yes I think I know exactly where that is only think I’m confused about is my tree has one line connected to two ports so tied into its self and one to the brakes if that makes any sense I’ll take a pic when I get home and post but this helps a lot thanks 
Someone simply looped the two ports together as they didn't have a correct vacuum cap. 

edit *** Don beat me to it... ;)

 
Last edited by a moderator:
I should have mentioned that the open port on my tree is for the thermal temp switch in the air cleaner for clarity. Mine has nothing else connected. 

Fwiw, I run my distributor on ported vacuum, not manifold. But that's another discussion!

 
Thanks everyone when I get home I’ll post a few pictures but it’s all starting to make sense appreciate everyone’s input glad I joined this forum

 
So if I can use either one of these ports I highlighted with a arrow right?

3D704A32-2B7A-4D87-A6A5-0D3B4D33B846.jpeg

 
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