Classic Mustangs (Tech) Technical discussions about the Mustangs of yester-year.

vacuum leak

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Old Feb 20, 2012 | 12:57 AM
  #1  
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oxfordbp
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Default vacuum leak

I replaced the intake to spacer and carb to spacer gaskets and still have a leak somewhere back here....





I found the leak in this area via spraying starter fluid at idle and the idle would jump.
Old Feb 20, 2012 | 01:39 AM
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The studs for the carb seem like they are too short and you are not getting enough of the threads to get a proper torque on the nuts. I would get some longer studs and inspect all the mating surfaces to ensure everything is clean and flat. Longer studs or try removing the washers from under the nuts. They didn't have washers from the factory.
Old Feb 20, 2012 | 02:07 AM
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I assure you they are torqued pretty good. However, I will try your advice.
Old Feb 20, 2012 | 10:45 AM
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is there a way (spraying) to isolate it further? the exact location.
the gasket in carb looks new as well, maybe that's dodgy?
Old Feb 20, 2012 | 11:06 AM
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I would get a can with the little straw that goes in the nozzle..That way you should be able to isolate exactly where the leak is when you are spraying.
Old Feb 20, 2012 | 12:02 PM
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Good idea frdnut and Kalli
Old Feb 20, 2012 | 12:03 PM
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Oh and since that picture I have rebuilt the carb, so all new gaskets.
Old Feb 20, 2012 | 01:54 PM
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You should always check for flatness of the mating surfaces. If someone in the past over tightened the the carb then it can bend the ears down and cause leaks. Check the spacer too. Nicks or bumps in the spacer can casue problems. Either way you should really tear it down to see what is going on.
Old Feb 20, 2012 | 02:02 PM
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Originally Posted by 67t5ponycoupe
You should always check for flatness of the mating surfaces. If someone in the past over tightened the the carb then it can bend the ears down and cause leaks. Check the spacer too. Nicks or bumps in the spacer can casue problems. Either way you should really tear it down to see what is going on.
Good point. I guess its just a good excuse to upgrade to a 4v! At least thats what Im telling my wife!!!
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