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Working on tuning a 65 A code. It is nearly all original. I am looking for advice on how to test the vacuum. The only vacuum line I see is to the distributor, and its a hard line with what looks like a brake fitting. The spacer under the carb has no opening on the back since it has no PCV valve. I don't see another vacuum port on the 4100. Other than find a threaded line to cut and put a hose on it in place of the vacuum advance line, is there another way? I don't see how it was tested originally in my shop manual.
 

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The vacuum port on the side that looks like brake line and goes to the distributor is timed with throttle opening, so no good for idle, but you can connect it to the port at the back of the intake that would go to the auto trans or power brake booster.
 

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You need manifold vacuum and the line to the distributor is ported vacuum, won't work. Look for a manifold vacuum port on the back of your intake like this one has.


746599
 

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Question on the 4100 carburetor what is this for circle in red on photo ?
 

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64 1/2 D Code Coupe,
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Question on the 4100 carburetor what is this for circle in red on photo ?
That's the heat tube connector for the thermal choke. Your heat tube is obviously missing. The tube connects to a pot on the passenger side exhaust manifold.
 

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Any chance you have more details on what parts you bought or where? That's what I will probably have to do as well.
I don't recall exactly, but I think I used an 3/8 NPT to 1/8 NPT brass reducer and then inserted a 1/8 NPT male to 3/16 brass hose barb fitting. I used plumbers tape and purchased a set of Dormon vacuum caps. All from Summit.
 

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I don't recall exactly, but I think I used an 3/8 NPT to 1/8 NPT brass reducer and the inserted a 1/8 NPT male to 3/16 brass hose barb fitting. I used plumbers tape and purchased a set of Dormon vacuum caps. All from Summit.
Also available at most NAPA stores if you don't want to wait for them or pay for shipping
 
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