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Discussion Starter #1
I rebuilt my Autolite 2 barrel on my 68 Cougar a few months back since the car had sat for a long time. It kept changing RPMs while at idle and I assumed it was a vacuum problem. After replacing all vacuum lines and not fixing the problem I took the car to a mechanic who is supposed to be good at engine issues. His comment was that unmetered fuel was flowing from the carb and so it would need a rebuild. The cost is too much to have someone else do the rebuild (might as well buy a new one). Since I'm the one who rebuilt the carb I am trying to figure out what I might have done wrong. I would like to fix this myself if possible and am willing to buy another kit if I need to. Any ideas? I had heard that there might be an issue with the manifold gasket since this was a NAPA kit.
Thanks
 

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Unmetered fuel is fuel that is getting into the intake without passing through the normal idle circuit or through the jets when the throttle is opened. I'm not as familiar with Autolite carbs as I am with Holleys, but there are a couple things you might check.

Make sure that the float level is set correctly. If you are getting too much fuel in the bowl it will force its way through the jets, even at idle. Make sure that everything is tightened correctly. Make sure you didn't accidentally leave out an o-ring or gasket. Make sure you aren't getting too much fuel pressure as this will also overfill the bowl.

Good luck!

Mike...
 

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Discussion Starter #4
Bad69cat - Thanks for the link. I'm going to tear down the carb again and carefully inspect everything as I take it off to see if I pinched something or just did't adjust it quite right. I used to rebuild Carter and Rochester carbs when I was a kid and didn't have this problem but hey, I'm older now so who knows what I might have missed in my desire to get everything up and running again.
 

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It sounds like the timing is not set correctly. Surging is seldom caused by a carburetor problem. More likely the timing is too advanced or retarded. How much centrifugal advance do you get at 3000 RPM with the vacuum advance plugged? What is the base timing at idle with all vacuum ports plugged and the vacuum advance disconnected? What is the total timing at 3000 RPM with the vacuum advance connected?

Does the vacuum advance work, and is it connected properly? Do you have leaky headlight motors or brake booster? Is the car equipped with factory air? If so, are the AC vacuum motors leaking? Does the car have tilt - away? Are the tilt - away cannister or vacuum motor leaking?
 

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That's another goog point - you may be better off to plug off the vac lines - see how it runs then. Then you can start introducing va lines back in to see which ones start causing troubles and work your wya through that part of the system. At first it sounded like you were already there - but after re-reading your first post sounds like we can't assume the mechanic took a good look at the whole system.......the old if you want it done right - you gotta do it yourself!
 
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