carbking Posted March 30, 2014 Share Posted March 30, 2014 Perhaps one of the most misunderstood (that is thought to be understood) terms in carburetion is the carburetor type.I get questions daily like:"My owner's manual states my car is equipted with a Stromberg AAV-26 carburetor, where can I get one?".The AAV-26 is a TYPE or STYLE of carburetor. Based on the AAV-26, I can tell that this is a Stromberg 2 barrel, S.A.E. size 2, with vacuum power system, and a hot air choke. Other than than..............nada!!!Allow me to change types to one with which I am extremely familiar, the Carter AFB (aluminum four barrel).Carter produced 505 DIFFERENT type AFB carburetors (doesn't not include the current clones) in sizes from 400 CFM to 939 CFM. These carburetors were designed to be used on 505 DIFFERENT applications of engine size from 170 CID 6 cylinders to 460 CID 8 cylinders, some with standard transmission, some with automatic transmission, some for use with air conditioning, some for use with smog emissions, and some for all-out auto racing.But they are ALL Carter type AFB carburetors, and for the most part, NOT directly interchangeable.Each of these carburetors have a specific identification number. From the identification number, if one has the necessary books, one can determine the internal characteristics of a specific carburetor.Now, back to the Stromberg AAV-26.I haven't gone through all the data to count the various AAV-26 carbs, but I did a MIN/MAX on my database, and they were produced for engines from 250 to 356 CID. There are several DIFFERENT internal venturi sizes of the AAV-26 (none of which are normally specified in the car owner's manual). The shop manual or the parts manual MAY give the actual part number for the carburetor in question. Then one knows exactly what one is looking for.The point that I am trying to make in a wordy fashion, is that simply stating a carburetor type or style or model is no more useful that stating "my vehicle came with Firestone 15 inch tires".If I remember correctly, my own B-18 Volvo has 670x15 tires. I wonder how well those would perform on either my pickup-truck or a circle-track racer.Finally, can one carburetor of a given type be converted into another carburetor of the same type? The answer is an indefinite maybe, depending often on whether the individual paying for the conversion is independently wealthy, and no longer wishes to remain so! And rarely, but occasionally, it can be done fairly easily.Jon. Link to comment Share on other sites More sharing options...
padgett Posted March 31, 2014 Share Posted March 31, 2014 (edited) Well sorta. the special one developed for Pontiac (939cfm ?) was really a ATB not AFB.ps leaky synapse fired: was that a 3636 ? Edited March 31, 2014 by padgett (see edit history) Link to comment Share on other sites More sharing options...
carbking Posted March 31, 2014 Author Share Posted March 31, 2014 Hi Padgett - you have the correct number .....3636s. Carter did classify the carb as an AFB. It has been enthusiasts that have called it a three-barrel. It is listed as a four barrel in the Carter files.Jon. Link to comment Share on other sites More sharing options...
ojh Posted March 31, 2014 Share Posted March 31, 2014 Can you elaborate on an 'indefinate maybe', that is a term I'd hear from a microsoft engineer.Just kidding Jon, Just kidding! Link to comment Share on other sites More sharing options...
Dandy Dave Posted April 1, 2014 Share Posted April 1, 2014 Carter AFB. I think that is what is on my 82 Buick Riv. Ragtop. 307 V8. I gave it a good cleaning and rebuild kit a few years back. Woke the old girl right up. I'm use to one barrel up draft Holley NH's and such. Dandy Dave! Link to comment Share on other sites More sharing options...
GLong Posted April 1, 2014 Share Posted April 1, 2014 Hi Jon, I agree that it is misunderstood that a 'TYPE' of carburetor is a very general description of the CORRECT MODEL of a 'TYPE' of carburetor. BUT as you mentioned: the owner's manual often leads the owner down that path by just stating the 'TYPE' of carb, not the full model, and specifications. I've learned this from the Stromberg O-3 used on Series 81 Pierce Arrow cars in '28. An O-3, which is cast into the carb body is a very general description for the carb.. there appears to be more than 10?, maybe 20? different versions of the O-3 that at first glance [walking by a table at a swap meet] is the correct carb.. And worse, there is no way but to KNOW the correct carb, and all the right items that need to be on the carb to KNOW that the one in your hands is the correct carb.. That's where guys like YOU come in: and help educate us.. but you have to educate each and everyone of us, since rarely do we find any information but from a carb expert.. like you.. I understand your frustration, having to go through the process of teaching each person that calls to do business with you can be tiresome and tedious.. especially with the various personalities we all have.. Nothing like a know-it-all guy who calls you for help, and proceeds to not listen to you, yet he came to you, for help, right ?? Thanks for the help you do provide on this forum, I've learned a lot by reading your posts. GLongBy the way, I need an old 'Stromberg' one barrel updraft carb for my 'Rarest-Mobile' do you have one? Just kidding.. Link to comment Share on other sites More sharing options...
padgett Posted April 1, 2014 Share Posted April 1, 2014 OK, the short form is that a carb is a poorly controlled leak that uses the venturi principle to create a low pressure area that sucks the gas into the intake airstream. Everything is fine so long as you do not go sonic at which point things go wonkey.You can mix and match as long as you know what you are doing (I had a really sweet running Corvair Corsa with an Oldsmobile quadrajet onnit). OTOH if you are points judging a 70 Pontiac Judge RA IV with a four speed it had best have the proper carb (7040273 and not a 7040272) or at least the right numbers in the right place.Key here is that just about everything related to carbs is documented somewhere, it is just in manuals that are not seen at swap meets (and I suspect Jon has all of them) and a dispute will probably come down to who has the best documentation (and factory parts books often lists the service part and not the original - why no GM car came off the line with an R59 installed).So if you really need it correct you assemble all available documentation and have it reviewed by an expert before going to an important show. The problem is separating Those Who Know from all of the wannabes. If not let me tell you the story about the repopped PF-23s that had the lettering upside down... Link to comment Share on other sites More sharing options...
Beltfed Posted April 1, 2014 Share Posted April 1, 2014 Mr. CarbKing, thank you for the information and insight. As I move from street rodder into the world of restorer I find that guys like you are invaluable for the information you process. I spent half a day today watching in wonderment as Jim Durall put my Columbia 2 speed rear end together. As an engineering type guy I just couldn't believe the way he worked on this rear end that was 70 years old. I felt like I was in a garage in 1946. Keep up the good work and please forgive us "grasshoppers". Link to comment Share on other sites More sharing options...
Dandy Dave Posted April 2, 2014 Share Posted April 2, 2014 If not let me tell you the story about the repopped PF-23s that had the lettering upside down...Ouch. Must have been re-popped somewhere over seas. Dandy Dave! Link to comment Share on other sites More sharing options...
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