Identify Quadrajet
Figures. I always seem to get the oddball stuff
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As 78silver78 has already indicated, the first four casting numbers for a production carburetor should be "1705" (used 1976-79) or "1708" (used 1980-up).
The fifth digit denotes the last numeral of the application year. (presume 1981)
The sixth digit is typically a "1" or a "2" it indicates the original application is federal - a "4" or a "5" would indicate a California application. (presume California)
The seventh digit indicates division application with "0" , "1" , and "2" used by Chevrolet; "3" used by Cadillac; "4" used by Buick; "5" used by Oldsmobile; "6" and "7" used by Pontiac; and "8" used by Checker and Marine. (presume Checker or Marine)
The eighth digit typically is transmission usage with even numbers often automatics and odd numbers often manual transmissions - not always true. (presume automatic transmission)
Hope this helps.
Last edited by mapman; Aug 9, 2011 at 06:28 PM.

Tips on identification of various carburetors
Carburetor Identification Service
Carter, Holley, Marvel, Rochester, Stromberg, Zenith
Carter
Brass Series (A,C,G,H) – (1909 – 1922) 1 barrel updraft (have no information to further identify these units)
Brass Bowl Series (DFT08, DR0, DRH0, DRJH0, DRJX0, DRJH08, DRX0, RAJH0, RAJX0, RAKX0, RJH08, R0, RT08, RX0) – (1923 – 1932) (1 barrel updraft) red cardboard tag (some later service replacements tagged with a triangular brass tag)
U Series (U-1) (1932) brass tag
W Series (W-0, W-1, WA-1, WE, W-2) - (1932 – 1949)(1 barrel) triangular brass tag; also, code number stamped under base
W Series (WCD, WD0,WGD) – (2 barrel) (1936 – 1967) metal tag; also code number stamped under base
W Series (WCFB) – (4 barrel) (1952 – 1965) metal tag; also code number stamped under base
AS Series – (1 barrel) (1956 – 1963) metal tag
RBS Series – (1barrel) (1963 – 1974) metal tag; also some (not all) stamped id number on edge of flange
AFB Series – (4 barrel) (1957 – 2001) metal tag: also some units stamped on edge of flange, some units stamped center of bowl in rear, some units stamped along bowl – airhorn seam in front, some units NOT stamped (tag only)
BB Updraft Series – (1 barrel) (1932 – 1963) rectangular brass tag
BBR Series (BBR-1, BBR-2) – (1 barrel) (1933 – 1938) rectangular brass tag
BBR Series (BBR-1, BBR-2) – (1 barrel) (1939 – 1960) letter number combination stamped on side of airhorn strengthening vane
BBS Series - (identified by tag only, once the tag is removed, identification is extremely difficult
BBD Series - identified by tag only, once the tag is removed, identification is extremely difficult
YF Series (YF, YFA) - most O.E. carbs stamped with the number followed by letter ‘S’ on center section (bowl)
UT Series – identified by tag only, once the tag is removed, identification is extremely difficult
N Series (N, ND, NRD) – some stamped on edge of flange, others tagged
Carter numbering systems. Three different types of numbering systems are found on Carter produced carburetors.
(1) On carburetors built for Chrysler Corporation, a series of 3, 4, or 5 letters and numbers; i.e. EV1 or D6H2.
(2) On carburetors built for Ford Motor Company, the “Ford” numbering system which is “lnll – l(l)(l)” or letter, number, letter, letter dash letter (possible letter) (possible letter) i.e C5VF-A. This system is codified in that the first letter is the decade (B=1950’s, C=1960’s, etc.); the number is the last digit in the year; the 3rd and 4th letters (before the dash) represent the vehicle model (VF=Lincoln); and the letter or letters after the dash are a modifier which distinguishes the exact application. Thus in the example C5VF-A, the carburetor would have been the first application for Lincoln in the year 1965.
(3) The traditional Carter numbering system which consisted of 1, 2, 3, or 4 digits; followed by the letter “S”, possibly followed by another letter. It is extremely doubtful that any of the single, double, or early triple digit tags will appear; as they were produced before 1930 and were constructed of red cardboard. The metal tag appeared about 1930 with tag numbers of about 300s. The 4 digit tag appeared in 1952, and was continued on until the end. The letter S and following letters, when present, have caused much speculation (mostly incorrect). In Carter’s terminology, an individual part such as an idle mixture screw was a single part; whereas two or more individual parts sold together such as a needle, seat, and gasket were sold as an “assembly”. Carter used the suffix letter S to denote assembly. Since all carburetors are composed of multiple parts, the letter S was appended to all carburetors using the traditional numbering system i.e. 938s. If a significant engineering change was made to the carburetor, the letter “A” would be appended to the S (i.e. 938sa). A second change would have the letter A replaced by the letter B (i.,e. 938sb). The highest engineering change of which I am aware is 4 i.e.938sd. Contrary to popular belief, the S DID NOT mean standard transmission, nor the SA automatic transmission.
Holley
Marvel
Updraft – brass bowl – must be identified from pictures of actual linkage and internal specifications (no identification numbers)
Updraft – diecast bowl – an identification number is stamped in tiny numbers on the underside of the bowl, or on the edge of the carburetor mounting flange. The number will be in the format 10-nnnn, where nnnn is some number LARGER than 500. Some Pontiac and Oakland units have a stamped “O” or “P” preceding the 10.
Downdraft – an identification number will be stamped SOMEWHERE on the outside surface of the carburetor in tiny numbers. Areas to look: the bowl cover, above the float; the edge of the flange of the bowl where it fits to the throttle body, on the throttle body itself.
The rest of the story – READ THIS. Marvel carburetors MAY have two DIFFERENT identification numbers, depending on if the carburetor were sold individually as a carburetor, or as a combination of carburetor and heat riser assembly. Generally, these numbers will differ by one or two digits. Thus the Marvel carburetor for a 1930 Buick series 60 may be stamped 10-753 or it might be stamped 10-754 (exact same carburetor) depending on how the carburetor was sold! Remember that the 10- number MUST be larger than 500. Marvel also used a 10- number less than 500 as a CASTING number for castings. These numbers are physically much larger, and often will be mistaken for the ID number as the ID number is much smaller physically. Casting numbers are not unique, and in general may not positively identify Marvel carburetors.
Rochester
AA Series – (1949, 1950) (2 barrel) triangular metal tag
B Series (B, BC, BV) – (1949 - 1967) (1 barrel) triangular metal tag.
BB Series – (1951) (2 barrel) triangular metal tag
2G Series (2G, 2GC, 2GV) – (1955 - 1967) (2 barrel) triangular metal tag
2G Series (2G, 2GC, 2GV) – (1968 – up) (2 barrel) roll stamp on side of bowl
4G Series (4G, 4GC) – (1952 – 1967) (4 barrel) triangular metal tag
H Series (H, HV) – (1960 – 1967) (1 barrel) triangular metal tag
H Series (H, HV) - (1968, 1969) (1 barrel) roll stamp on side of bowl
Monojet – (1968 - up) (1 barrel) roll stamp on side of bowl
Quadrajet – (1965 – 1967, some early 1968) (4 barrel) round metal tag pressed into side of bowl
Quadrajet – (1968 – up) (4 barrel) vertical roll stamp on side of bowl
R Series – (R, RC) – (1962, 1963) (1 barrel) triangular metal tag
Tags: Tags beginning in 1949 were brass. The metal was changed to aluminum approximately 1956. There appears to be some time overlap in the different series. The aluminum tags were color anodized on the top side. The color used was a code to help identify the carburetors. A few times in carburetor cleaner, and the color disappeared to a natural aluminum finish. The triangular tags were located under one of the screws holding the air horn to the bowl. The round tags (1965 – 1967 quadrajets) were pressed into an indent in the side of the bowl directly behind the primary throttle arm.
Roll stamps: Beginning in 1968, all Rochester carburetors were "roll stamped" with the identification number on the side of the bowl. These are "stamped" or "recessed" numbers, not "raised" as discussed below.
Other identification numbers: A very few 4G Series carburetors in 1957 only were stamped with the last 4 digits of the identification number on top of the air horn. Very early B series have the last 2 digits of the identification number stamped on the airhorn.
Casting (raised) numbers: Raised numbers appearing on various castings are so-called "casting" numbers. These numbers were used by Rochester to identify a casting "blank" PRIOR to machining. A casting could be machined into different parts. As an example; consider the throttle body of the 1957 Pontiac tripower: the front carburetor has no idle screws in front, and an 1/8 inch pipe tap in the rear; the center carburetor has idle screws in front, and an 1/8 inch pipe tap in the rear; the rear carburetor has neither idle screws nor pipe tap. ALL have the same casting number. IT IS IMPOSSIBLE TO IDENTIFY ROCHESTER CARBURETORS FROM CASTING NUMBERS ALONE!
Carter built quadrajets: Carter Carburetor Company of St. Louis produced millions of quadrajets under license from GM from 1966 through 1979. These carburetors carry the exact same identification as their Rochester counterparts, and parts are directly interchangeable. Carter also produced "aftermarket" replacement quadrajets, which will be identified by the traditional Carter part number (4 digits, followed by the letter "S"). An example of this numbering system would be 4675S, which is identical except for the number to 7028262.
Rochester part numbers and application: Virtually all Rochester carburetor numbers produced from 1949 through 1974 are included in the application listings on this website.
Stromberg
The following applies to Stromberg-USA carburetors, and does not apply to Stromberg carburetors produced elsewhere:
Stromberg began stamping a ‘code’ number on virtually all O.E. (original equipment) carburetors beginning in 1935 up through the end of production in 1974. Most of the carburetors produced in the late 1930’s were stamped on the throttle body. Others were stamped on the airhorn. After 1940 this trend was reversed, and most carburetors were stamped on the top surface of the airhorn along one of the edges. Replacement carburetors produced during this period were generally identified by tag only (although a few replacements were stamped). The stamped ‘code’ is in the format ‘ccc-nnne’ where ccc is a one, two, or three digit code representing the company for which the carburetor was produced (ie 2=Ford, 4=Chrysler, 7=Buick, etc.); nnn is a one, two, or three digit number representing the next sequential number of carburetor sold to the company in ‘ccc’; and e is a letter (if present) representing the engineering change status of the carburetor. An example would be 7-69A which is decoded as 7 (Buick); 69 (the sixty-ninth type of carburetor sold to Buick – this one fits a 40 series in 1949); and ‘A’ meaning one engineering change to the original specifications. A second change would be 7-69B. Stromberg used both rectangular (held in place by a screw) and round (riveted in place) tags during this period, on those units which were tagged.
Stromberg carburetors produced prior to 1935 can easily be identified as to type, as it is cast onto the carburetor; however complete identification is impossible unless one has prior knowledge of the carburetor being identified; and can be quite difficult and time consuming for even someone with the original prints.
Zenith
The following applies to Zenith-USA carburetors, and does not apply to Zenith carburetors produced in elsewhere:
Zenith carburetors produced from about 1932 to 1980 have a round tag, approximately the size of a US dime, riveted to the body of the carburetor. Original equipment carburetors will have two numbers stamped on this tag. The outer circle will be the O.E. part number (ie Allis Chalmers, GMC, IHC, etc.). The inner circle will be the Zenith number. Aftermarket carburetors made during this period will have the Zenith part number only on the tag.
Zenith carburetor produced after about 1980 will not have the round tag, but will have a tiny number stamped (never raised) in a semi-circle on the body of the carburetor.
Some Zenith carburetors produced in the 1920’s up to about 1935 have a long thin rectangular tag with the Zenith number stamped.
Identification of Zeniths other than above is difficult.
The following chart has been copied (with permission) from a factory Zenith publication, and will help the hobbyist understand the meaning of the Zenith models. This does NOT identify individual carburetors, only the identification number can be used for positive identification:
A – designates a carburetor where the throttle shaft is parallel to the air shutter shaft (with normal air intake).
B – designates a carburetor where the throttle shaft is at right angles to the air shutter shaft (with normal air intake).
BB – same as above but with fly opening opposite of above (B).
C – vacuum pump, NO power jet.
DA – duplex carburetor with one throttle shaft.
DB – duplex carburetor with two parallel throttle shafts.
E – elbow air intake ( for downdraft, horizontal and updraft carburetors, when the angle of the air intake differs from that of the standard of the series)
F – governor connection, opposite side from bowl or on left side.
G – a carburetor using natural gas or a combination of gasoline and natural gas for fuel
GM – special 30 series to General Motors
I – special for International Harvester, Inc.
J – back-suction economizer
L – large bowl ( model 267 carburetors)
LP – liquid petroleum gas carburetor
M2 - marine carburetor with screws, brackets, levers, and shafts in brass.
M3 – marine carburetor with brass bowl and iron barrel
M4 – marine carburetor, all brass
N – special for Novi governors
O – offset throttle shaft (only in case it differs from the standard).
P – pump (14 and 16 models)
R – governor connections, same side as bowl or on right side
S – straight thru for updraft carburetors
T – balanced or sealed bowl vent
U – universal replacement carburetor special flange c.c
V – vacuum operated power jet if the standard of the series has mechanical pump or no pump
W – vacuum pump AND power jet
X – oversize flange and/or bolt location
Y – undersize flange and/or bolt location
The following for letters FOLLOWING the carburetor size:
C – automatic choke
G – gas valve attachment for LPG
R – Facet regulator or governor
RP – Pierce governor
RZ – Mechanovac governor
S – special flange
SD – LP starting device
hope this helps you.........





Recheck your numbers. Should be " 1705 " or " 1708 "









