Auto Parts: Carburetor, quadrajet carb, secondary circuits

Question
Mike,
 I have a used 327 Chevrolet 4 barrel, intake manifold, casting #3844459. Can you check your books/sources & tell me what the original manufacturer, & part # carburetor was on this manifold. My small cross reference just says 1963-1965 327 4-barrel manifold, no carburetor name or number. It seems to me that GM did so much research & engineering to match their engine products up I would like to either get an original/rebuilt or a newer carburetor closely matching the original. Any suggestions would help. Thank you.
Al

Answer
    Hmmm.  Is this a spread-bore carb?  In other words, are the front and rear holes the same size, or are the rear holes bigger?  If the rear holes are bigger, which I believe they should be, then it uses a Quadrajet carb.  GM sold replacement Quadrajets under the Delco brand for years, until the late '80's.  Anyone who was in the parts business back then knows that they superseded Quadrajet part numbers on a weekly basis.  If you don't have the carb that goes with the car, your chances of finding the correct one are nil.  On the other hand, the reason that they could supersede these part numbers so frequently is that they all pretty much work the same.  If you look in Summit's catalog you will see that they offer a couple of different versions, depending on the location of the fuel line inlet and the type of choke thermostat.  If you just go with the electric built-in choke thermostat, and make sure that the fuel line inlet is compatible with your fuel line (bend yourself a new one and you won't have to worry about that), you should have a good, sophisticated carb that will make the same power as a Holley and get much better gas mileage.  The genius of the Quadrajet is the way the secondary circuits adjust themselves while the engine is running, much better than the power valve system used by Holley.  GM spent of lot of engineering time on these things, getting them exactly right for each model and, in later years, getting the mixture set so that the car would not pollute too much or plug up the converter.  For your purposes, these things are not all that important and, since the fuel we are using today is very much different from what was available back then, one of these replacement carbs will probably be closer to right than an OE unit.