The carburetor on my '72 Chevy has started leaking from the right rear. I will post some photos tomorrow. It all started last week when I was revving the engine a little to blow some water out of the tailpipe that had collected in there from the rain due to the way the car was setting. I may have kicked in the "four barrel" a couple of times. It seems like that butterfly is sticking open and not completely closing back and my dad says that is why it is leaking. I cleaned the carb with cleaner and even used some pb blaster on the mechanisms, but it still isn't closing. I closed it myself and haven't opened it back up (light acceleration) and drove it to the store the other day while gas was still cheap and filled the tank with gas. I got home and it seems like it may still be seeping a little, but it may have been the remnants of the pb blaster not evaporated? We rebuilt the carb about 3 years ago... not sure if it is going to require another one or not.
Check the mounting screws to the manifold, and make sure that you don't over tighten the air clean wing nut. The stud doesn't go down to the base, and it is easy to warp the top casting. Once you do this, it takes a professional to heat the top casting using the proper jig to straighten it.
Regardless of what you may have heard, Quadrajet carburetors are among the easiest to rebuild. Of course it helps to know how all the little doo dads are adjusted and such. I'd get a junkyard carb and take it apart to get familiar with them. All of the manufacturers put them on cars at one time or another and they prove to be very reliable and more than enough for a lot of power applications. (I used a 950 cfm Quadrajet on my Monte Carlo SS and it ran in the 11's consistently!) A Chilton's book or other manual can give you easy instructions on the rebuild. Also make sure to check for cracked lines and other thing like that. Cockroach Dave
Rebuild kits can run a bit expensive at around $50.00 bucks but all of them are basically the same parts with a few added accessories. Be sure to map all the vacuum lines before you remove any of them. Have fun. Its supposed to be fun!
Usually, an overfueling problem like that is a sunk float or leaking jet wells (idle well leaks are common on '60s and some '70s Q-pukes). However, this sounds like it's something really unusual; the secondary needles come to mind. Pull them with their bracket and verify the RR one is not bent. Look down inside to the jet with a bright flashlight and verify the jet doesn't have a piece of something sitting on top of it, holding the needle up.
