If you're seriously considering rebuilding your old carburetor
yourself (which I would recommend), you may want to pick up this book:
Carter Carburetors by Dave Emanual, ISBN: 0931472113. Available at
Barnes and Noble (http://shop.barnesandnoble.com/booksearch/isbnInquiry.asp?isbn=0931472113),
among other places.
Granted, it's got a lot of info you won't need unless you want to
tune your carburetor by grinding and replacing parts, but it does
provide a good introduction to carburetor theory and operation, as
well as the specifics of Carter models. On the other hand, you can get
90% of what you need from the shop manual. If you don't have the shop
manual, BUY ONE. It's the best money you'll ever spend on your car.
They pop up on eBay all the time for ~$15.
Before you start tuning your carburetor, there's a common
misunderstanding that needs to be addressed: the "idle screws" on the
front of the carburetor adjust the amount of fuel/air mixture that is
pulled into the carburetor bore at idle. There are 2 things to note
Completely disassemble the carburetor and clean it before you add
the new gaskets, valves, etc. in the rebuild kit. I mean take out
everything that will come out (shafts, plates, valves, etc.) before
you clean it. A lot of these older carburetors get gunked up in places
like bleed vents. Merely replacing parts won't address this problem;
you need to clean the carburetor. You can buy a gallon of carburetor
cleaner complete with a parts basket at your local parts store (or
Auto Zone, anyway) for about $12. Soak it overnight, and put it back
together the next day. I generally scrape off all (or most) of the
outside crud with a wire brush before I soak it, then blow everything
out with high pressure air when it's done. Blast air through every
hole you can find (needle valves, float valves, bleed vents, etc.). If
you don't have a compressor, a bicycle pump will do (but your lungs
won't). A little dirt in the wrong place (e.g. idle bleed vent) can
cause big performance problems.
Don't polish the throttle and choke shafts aggressively to clean
them. All you need to do is take off whatever varnish and/or carbon
may be on them. If you take off too much metal, you'll have a sloppy
fit, which will create a vacuum leak and screw up your air/fuel ratio.
It's also possible that the shafts could be loose because the holes
are worn, but that doesn't happen very often with the AFB because the
throttle body casting is so thick.
Don't forget to clean the choke (including the piston). It
frequently clogs up with carbon, so your choke sticks. If you want to
go whole hog, add an electric choke. See
here for more information.
Lastly, the rebuild kit will often have different specifications
than the chassis manual for things like float drop. I always go with