Pontiac GTO Forum - View Single Post - technical questions to steering gearbox and vacuum gauge on a 1965 grand prix
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post #10 of (permalink) Old 08-03-2014, 01:48 PM
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Location: Gastonia, NC - Born & raised in Connecticut - 31 years
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Originally Posted by GP65 View Post
Hey Jim,
thanks a lot for your answer.
That gives me an idea how this system should run.
I will try the things you said me, and then see if the "missing vacuum line" gets found and the vacuum gauge will run again.

IŽll post one more picture of the carb, maybee you can see some details that you havnŽt been able to see in the first pictures.

best regards

Looking at the carb, you do not have the vacuum port in the front between the idle screws. I did some web searching and found a carb just like yours and it was a factory Pontiac 1966 Carter AFB, so your carb looks to be original.

Some AFB carbs have the big vacuum port at the rear which I believe connects the vacuum hose to power brake booster? From the photo, the big vacuum hose looks like it goes down near the distributor. I found a photo of a 1966 Tr-Power and the hose in question goes to the PCV valve which is at the rear of the intake? If so, then this is correct. The problem I see is the other end.

Where does the other end lead to? Later Pontiacs have the PCV valve in the front and I thought that was where that end was going. Does th hose connection in front of the carb go to a vacuum port/source that is directly tapped into the manifold? If so, then I don't think you need that plastic "T" fitting and the hose should go directly from the PCV valve at the rear to the manifold vacuum port fitting. Then simply cap off the small vacuum port that is tied into that plastic "T" fitting.

Make sense? Eventually we will get it figured out.
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