The Chevrolet small-block engine is a series of automobile V8 engines built by the Chevrolet Division of General Motors using the same basic, and for a V8, smaller engine block. These blocks are referred to as the “Gen I” small-block, the subsequent “Gen II” LT, and “Generation III/IV” LS, along with the current “Generation V” (LT/EcoTec3) engines.
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The Chevrolet big-block is a series of large displacement V8 engines that were developed and used in the 1950s through the 1970s. Chevrolet had introduced its popular small-block V8 in 1955, but needed something larger to power the medium-duty trucks and its heavier cars that were on the drawing board.
Gen I small-block Chevy engine. This drawing is of the 1967 version of the 302 cid Chevrolet. Drawings by David Kimble.Production of the original small-block began in the fall of 1954, for the 1955 model year, with a displacement of 265 cid, growing incrementally over time until reaching 400 cid in 1970. Several intermediate displacements appeared over the years, such as the 283 cid that was available with mechanical fuel injection, the 327 cid as well as the numerous 350 cid versions.
Decoding the Tri-Five Chevy 55 56 57 Passenger Car VIN Vehicle Identification Number (VIN): The VIN tag is located on a stainless steel plate that is spot welded to the driver's side front door jamb. Chevy engine numbers are serial numbers located on the engine lock of Chevrolet vehicles. These number contain valuable information about where and when the engine was manufactured, as well as its capacity and statistics. View your *Vehicle Profile* service history, recalls and warranty information at Chevrolet Owner Center.
Although all of Chevrolet’s siblings of the period (Buick, Cadillac, Oldsmobile, and Pontiac) designed their own V8s, it was the Chevrolet 350 cu in (5.7 L) small-block that became the GM corporate standard. Over the years, every American General Motors division, except Saturn, used it and its descendants in their vehicles.
In all, over 90,000,000 small-blocks have been built in carbureted and fuel injected forms since 1955. The small-block family line was honored as one of the 10 Best Engines of the 20th Century by the automotive magazine Ward’s AutoWorld.
Here is a list of casting numbers, along with their original applications.
Generation I Small-Block
10036033 Small Block V8 350, 4-bolt, Goodwrench crate engine, 2-piece rear seal
10051182 Small Block V8 2 bolt, Bow Tie block, 3.75-4.30 bore, 1-piece rear seal
10051184 Small Block V8 4 bolt, Bow Tie, 4.00-4.160 bore, 1-piece rear seal
10054727 Small Block V8 1986 350, 2-bolt or 4-bolt, one piece rear seal
10066036 Small Block V8 350, 4-bolt, Goodwrench crate engine, 2-piece rear seal
10066038 Small Block V8 1994 350, 4-bolt, Goodwrench crate engine, 2-piece rear seal
10090511 Small Block V8 1990 350, 2-bolt, LT5, Corvette ZR1, 375hp
10134996 Small Block V8 4-bolt, Bow Tie, aluminum, 4.125 bore, 2.65 main journals
10199001 Small Block V8 1993-1995 350, 4-bolt, LT5, Corvette ZR1, 405hp
10243878 Small Block V8 1996-1997 305, 2-bolt, Vortec truck, roller cam, 1-piece rear seal
10243880 Small Block V8 1995-1999 350, 4 bolt, crate engines and ZZ4, roller cam, one piece rear seal
Chevrolet Block Identification number locations. Photo from www.justanswer.com
140029 Small Block V8 1980-1984 350, 2 bolt
14010201 Small Block V8 1980-1984 305, 2 bolt
14010202 Small Block V8 1980-1984 305, 2 bolt
14010203 Small Block V8 1980-1985 305, 2 bolt
14010207 Small Block V8 1980-1985 350, 2 bolt or 4 bolt
14010209 Small Block V8 1980-1985 350, 4 bolt
14010280 Small Block V8 1979-1982 267, 2 bolt
14011064 Small Block V8 1983 350, 4 bolt
14011148 Small Block V8 1987-1989 350, roller cam, 1-piece rear seal
14016376 Small Block V8 1979-1982 267, 2 bolt
14016379 Small Block V8 1977-1979 350, 2 bolt or 4 bolt
14016381 Small Block V8 1980-1984 305, 2 bolt
14016382 Small Block V8 1979-1984 305, 2 bolt
14079287 Small Block V8 1986-1990 350, Truck
14088526 Small Block V8 1987-1989 350, roller cam, 1-piece rear seal
14088548 Small Block V8 1986-1988 350, 2 bolt or 4 bolt
14088551 Small Block V8 1986-1987 305, 2 bolt, 1-piece rear main seal
14093627 Small Block V8 1987-1991 305, 2 bolt, roller cam, 1-piece rear seal
14093638 Small Block V8 1987-1995 350, 2 bolt or 4 bolt, roller or flat tappet cam, 1-piece rear seal
14101148 Small Block V8 1987-1990 350, 4 bolt, 1-piece rear seal
14102058 Small Block V8 1987-1991 305, 2 bolt, roller cam, 1-piece rear seal
330817 Small Block V8 1972-1980 400, 2 bolt
3556519 Small Block V8 1958-1961 283, 2 bolt
355909 Small Block V8 1975 262, 2 bolt
355909 Small Block V8 1976-1979 305, 2 bolt
360851 Small Block V8 1975-1976 262, 2 bolt
361979 Small Block V8 1978-1979 305, 2 bolt
366245 Small Block V8 1978-1979 350, 2 bolt
3703524 Small Block V8 1955 265, 2 bolt, no oil filter
3720991 Small Block V8 1956-1957 265, 2 bolt
3731548 Small Block V8 1957 265, 2 bolt, no side engine mounts
3731548 Small Block V8 1957 283, 2 bolt, no side mounts
3737739 Small Block V8 1958-1964 283, 2 bolt
3756519 Small Block V8 1958-1962 283, 2 bolt
3782870 Small Block V8 1962-1967 327, 2 bolt
3789817 Small Block V8 1962-1964 283, 2 bolt
3789817 Blocks Small Block V8 1962-1967 327, 2 bolt
3789935 Small Block V8 1961-1964 283, 2 bolt
3790721 Small Block V8 1962-1964 283, 2 bolt, recessed oil filter boss
3790721 Small Block V8 1965-1966 327, 2 bolt, recessed oil filter boss
3791362 Small Block V8 1962-1967 327, 2 bolt, recessed oil filter boss
3792563 Small Block V8 1965 327, 2 bolt
3792582 Small Block V8 1964-1965 283, 2 bolt
3794226 Small Block V8 1958-1963 283, 2 bolt
3794460 Small Block V8 1962-1964 327, 2 bolt
3814660 Small Block V8 1968-1969 327, 2 bolt
3830944 Small Block V8 1963 327, 2 bolt
3834810 Small Block V8 1964-1966 283, 2 bolt
3834812 Small Block V8 1962-1963 283, 2 bolt
3837739 Small Block V8 1958-1962 283, 2 bolt
3849852 Small Block V8 1957-1966 283, 2 bolt
3849935 Small Block V8 1965-1967 283, 2 bolt
3858174 Small Block V8 1964-1967 327, 2 bolt
3858180 Small Block V8 1964-1967 327, 2 bolt
3858618 Small Block V8 1968-1976 350, 2 bolt
3862194 Small Block V8 1965-1967 283, 2 bolt, recessed oil filter boss
3862812 Small Block V8 1962-1964 283, 2 bolt
389257 Small Block V8 1967 302, 2 bolt
3892657 Small Block V8 1967 302, 2 bolt, Camaro Z28
3892657 Small Block V8 1967 327, 2 bolt
3892657 Small Block V8 1967 302, 2 bolt, Camaro Z28
3896944 Small Block V8 1967 283, 2 bolt
3896948 Small Block V8 1966-1967 283, 2 bolt
3903352 Small Block V8 1967 327, 2 bolt
3914636 Small Block V8 1968 307, 2 bolt
3914653 Small Block V8 1968-1973 307, 2 bolt
3914660 Small Block V8 1968 327, 2 bolt
3914678 Small Block V8 1968 302, 2 bolt, Camaro Z28
3914678 Small Block V8 1968 327, 2 bolt
3914678 Small Block V8 1968 350, 2 bolt
3932371 Small Block V8 1969-1973 307, 2 bolt
3932373 Small Block V8 1968-1973 307, 2 bolt
3932386 Small Block V8 1969 302, 4 bolt, Camaro Z28
3932386 Small Block V8 1969 327, 2 bolt
3932386 Small Block V8 1969 350, 4 bolt
3932388 Small Block V8 1969 350, 2 bolt or 4 bolt
393288 Small Block V8 1965-1967 283, 2 bolt
3951509 Small Block V8 1970-1971 400, 4 bolt
3951509 Small Block V8 1974-1980 400, 2 bolt
3951511 Small Block V8 1970-1972 400, 2 bolt or 4 bolt
3956618 Small Block V8 1969 302, 4 bolt, Camaro Z28
3956618 Small Block V8 1968-1969 327, 2 bolt
3956618 Small Block V8 1969 350, 2 bolt or 4 bolt
3956632 Small Block V8 1969 307, 2 bolt
3959512 Small Block V8 1962-1963 327, 2 bolt
3970010 Small Block V8 1969 302, 4 bolt, Camaro Z28
Drawing of an LS6 Small-Block Chevrolet engine.
LS Small Block
12550592 LS Small Block V8 1997-up 346, LS1
12559846 LS Small Block V8 1998-up 346, LS1
12560621 LS Small Block V8 1998-up 346, LS1
12562174 LS Small Block V8 1998-up 346, LS1
LT Small Block
10125327 LT Small Block V8 1992 350, 2 bolt or 4 bolt, LT1, reverse flow cooling
10125327 LT Small Block V8 1996 350, 2 bolt or 4 bolt, LT4, reverse flow cooling
10153558 LT Small Block V8 1991-1992 350, 4 bolt, LT5, Corvette ZR1, 375hp
W Block
3732755 W Block 1959-1961 348 CID
3732811 W Block 1958 348 CID
3751872 W Block 1958 348 CID
3755011 W Block 1959-1961 348 CID
3771705 W Block 1959-1961 348 CID
3782012 W Block 1958-1961 348 CID
3788068 W Block 1962-1963 409 CID
3795623 W Block 1961 409 CID
3798962 W Block 1962-1965 348 CID, Truck
3815707 W Block 1958-1961 348 CID
3830814 W Block 1963 427 CID, Z11, 4.312 inch bore, 3.65 inch stroke
3830814 W Block 1963-1964 409 CID
3839752 W Block 1962-1963 409 CID
3839754 W Block 1965 409 CID
3844422 W Block 1963-1965 409 CID
3857655 W Block 1962-1965 348 CID, Truck
3857656 W Block 1964-1965 409 CID
3860386 W Block 1962-1964 409 CID
3860387 W Block 1958 348 CID
3844422 W Block 1963-1965 409 CID
3857655 W Block 1962-1965 348 CID, Truck
3857656 W Block 1964-1965 409 CID
3860386 W Block 1962-1964 409 CID
3860387 W Block 1958 348 CID
Big Block Chevrolet
Chevy Truck Serial Number Decoder
10051107 Big Block V8 454, 4 bolt, Bowtie, MkIV, 9.8 deck, siamesed bores, 4.25-4.50 bore
10069282 Big Block V8 1990-1991 366 tall deck, 4 bolt, Mark IV, Tall deck
10069284 Big Block V8 427 tall deck, 4 bolt, Mark IV, Tall deck
Chevy Serial Number Decoder
10069286 Big Block V8 1990-1991 454, 4 bolt, Mark IV, Short deck
10114182 Big Block V8 1991+ 454, 4 bolt, Generation V
10114183 Big Block V8 1991+ 366 tall deck, 4 bolt, Generation V
10114184 Big Block V8 1991+ 427 tall deck, 4 bolt, Generation V
10134366 Big Block V8 454 tall deck, 4 bolt, Bowtie, Generation V, Tall deck
10185050 Big Block V8 454, 4 bolt, Bowtie, Generation V, Short deck
10237297 Big Block V8 1996+ 454, 4 bolt, Vortec 7400, L-29 Generation VI
10237299 Big Block V8 1996+ 427 tall deck, 4 bolt, Generation VI, 7.0L, truck
10237300 Big Block V8 1996+ 502, 4 bolt, Generation VI, 4.466 bore
12550312 Big Block V8 1996+ 427 tall deck, 4 bolt, Generation VI, 4.250 bore, fuel pump boss, clutch linkage pivot boss
12550313 Big Block V8 1991+ 454, 4 bolt, Generation V crate motor, Generation VI 4.25 bare block, fuel pump boss
12556110 Big Block V8 2001+ 496, 4 bolt, Generation VII 8.1L, Vortec 8100, Truck
12561357 Big Block V8 1996+ 454, 4 bolt, Generation VI
12561358 Big Block V8 502, 4 bolt, Generation VI
14015443 Big Block V8 1987-1990 454, 2 or 4 bolt, Mark IV, Truck or Motorhome
14015445 Big Block V8 1978-1990 454, 2 bolt or 4 bolt
14044807 Big Block V8 454 tall deck, 4 bolt, Bowtie, MkIV, CNC prep, Tall deck, 4.25 bore or 4.495 bores
14096859 Big Block V8 502, 4 bolt, Generation V, HO
24502504 Big Block V8 454, 4 bolt, Bowtie, Generation V, Race prep, 9.8 short deck height
24502506 Big Block V8 454 tall deck, 4 bolt, Bowtie, Generation V, Race prep, 10.2 tall deck height
24502572 Big Block V8 4 bolt, 4.5 bore Olds DRCE 2, 9.5 deck height
25534402 Big Block V8 4 bolt, 4.590 bore Olds DRCE 3, 9.25 deck height
326711 Big Block V8 4 bolt, aluminum, CanAm, 4.44 bores, steel cylinder liners
340220 Big Block V8 1968-1985 427 tall deck, 4 bolt
345014 Big Block V8 1970-1986 454,
346236 Big Block V8 1975-1976 454, 2 bolt
359070 Big Block V8 1970-1990 454,
361959 Big Block V8 1973-1990 454, 2 bolt or 4 bolt
364776 Big Block V8 1968-1985 427 tall deck, 4 bolt
364779 Big Block V8 1968-1990 366 tall deck, 4 bolt
3782870 Big Block V8 1968-1976 427 tall deck, 4 bolt
3824553 Big Block V8 1966-1967 366 tall deck, 4 bolt
3855961 Big Block V8 1965-1966 396, 2 bolt or 4 bolt
3855961 Big Block V8 1966 427, 2 bolt
3855962 Big Block V8 1965-1966 396, 4 bolt
3855977 Big Block V8 1966-1973 366 tall deck, 4 bolt
3869942 Big Block V8 1966-1967 427, 2 bolt or 4 bolt
3902406 Big Block V8 1967 396, 2 bolt or 4 bolt
3904351 Big Block V8 1967 427, 2 bolt or 4 bolt
3904354 Big Block V8 1966-1976 366 tall deck, 4 bolt
3916319 Big Block V8 1968 366 tall deck, 4 bolt
3916321 Big Block V8 1968 427, 2 bolt or 4 bolt
3916323 Big Block V8 1968 396, 2 bolt or 4 bolt
3925521 Big Block V8 1968-1985 427 tall deck, 4 bolt
3935439 Big Block V8 1968-1969 427, 2 bolt or 4 bolt
3935440 Big Block V8 1968-1969 396, 2 bolt or 4 bolt
3937724 Big Block V8 1968-1985 366 tall deck, 4 bolt
3937726 Big Block V8 1968-1984 427 tall deck, 4 bolt
3946052 Big Block V8 1969 427, 4 bolt, aluminum ZL-1, Mark IV
3946053 Big Block V8 1997+ 427, 4 bolt, aluminum ZL-1, 2nd version, Mark IV
3955270 Big Block V8 1969 427, 2 bolt or 4 bolt
3955272 Big Block V8 1969 396, 2 bolt or 4 bolt
3955274 Big Block V8 1968-1985 366 tall deck, 4 bolt
3955276 Big Block V8 1968-1973 427 tall deck, 4 bolt
3963512 Big Block V8 1969 427, 2 bolt or 4 bolt
3963512 Big Block V8 1970-1976 454, 2 bolt or 4 bolt
3969852 Big Block V8 1968-1984 366 tall deck, 4 bolt
3969854 Big Block V8 1969 396, 2 bolt or 4 bolt
3969854 Big Block V8 1970-1972 402, 2 bolt or 4 bolt
3969858 Big Block V8 1968-1984 427 tall deck, 4 bolt
399204 Big Block V8 1970-1971 509, 4 bolt, aluminum, CanAm, 4.5 bores, steel Cylinder liners
399293 Big Block V8 1977-1978 366 tall deck, 4 bolt
3999289 Big Block V8 1971-1979 454, 2 bolt or 4 bolt, some CE replacement blocks had four bolt main caps
3999290 Big Block V8 1968-1969 396, 2 bolt or 4 bolt, Truck
3999290 Big Block V8 1970-1972 402, 2 bolt or 4 bolt, Truck
3999290 Big Block V8 1972 402, 2 bolt or 4 bolt, Passenger
3999293 Big Block V8 1968-1990 366 tall deck, 4 bolt
3999294 Big Block V8 1968-1984 427 tall deck, 4 bolt
473478 Big Block V8 1977-1990 427 tall deck, 4 bolt
495102 Big Block V8 4 bolt, aluminum, CanAm, 4.5 bores
It is within very small circles that the Rochester Quadrajet is ever considered a performance carburetor. Although it was placed on many of the vehicles Chevrolet built from the ’60s until the late ’70s – as well as some Chrysler products – it still does not get the respect it deserves. When talking to guys about restorations however, it is highly regarded as the go-to carburetor.
Since there are so many variations of the carburetor and each one has a different factory application, we decided that giving you guys an identification guide would be beneficial for when you are scouring the swap meet or local junkyard for the correct unit for your car.
Although the Quadrajet is not as popular of a performance upgrade as some of the aftermarket brands, it is still a very good alternative for many spread-bore, four-barrel applications, especially when you are trying to find a little economy to go with your performance.
Few people still fail to realize the Quadrajet has a strong racing heritage within the Stock and Super Stock drag racing classes. In fact, there have been a multitude of record-holding Super Stock race cars that have run in the 9-second bracket with a Quadrajet on top of their manifolds.
How It Began
The Quadrajet was released in 1965, and since then, saw a long and fruitful life installed on GM cars until EFI took over. The Quadrajet was actually the successor to the previously-built Rochester 4GC carburetor that was manufactured from 1952 to 1967. This new carburetor was blended with what Rochester knew about carburetors, mixed with ideas from other manufacturers, (spread-bore design and vacuum secondaries). The Quadrajet became an instant success.
The Quadrajet carburetor was available on GM passenger and performance cars, as well as its trucks. Image courtesy www.chevytalk.com
When part-throttle cruising, the small primaries (1 3/32-inch for 750 cfm, and 1 7/32-inch for 800 cfm carburetors) deliver a higher velocity into the intake than other carburetors. This results in better fuel atomization going into the intake. This, of course, is dependent upon whether the fuel metering, float level, idle-screw setting, throttle-blade angle, jets, power valve, air bleeds, and needle valves, etc., are all properly set.
While there are some GM street-car enthusiasts that swear by the Quadrajet, they are also disliked by almost as many. The stigma surrounding the Quadrajet has to do with the perceived lack of performance capabilities, and because rebuilding them is not quite as easy as, let’s say, a Holley. Many even call them “Qaudrabog” carburetors because of the sound that occurs when the secondaries open.
The choke mechanism on a 4MV Quadrajet made use of a coiled spring that is mounted under a shield to the manifold.
Since this actually occurs when the carburetor is not properly tuned, it is an ill-conceived, derogatory name. Either way, parts are easy to find, and a properly rebuilt Quadrajet will perform just as well as many aftermarket units when used in a proper application. In fact, even Chrysler used Quadrajet carburetors in the late ’80s, proving their popularity over the Carter Thermoquad with the engineers at Mopar.
Model Differentiation
There were many models of Quadrajets used throughout the years, which tells of the versatility. The first few versions to appear were coded 4MC, which utilized a side-mounted integral choke, and the 4MV that made use of a manifold-mounted choke.
Benefits Of A Quadrajet
Economy: Since the Quadrajet has different-sized primary and secondary venturi, the small primaries make the carburetor more efficient than even a large two-barrel, or square-bore four-barrel. The smaller primaries act as a small two-barrel carburetor until the accelerator is pressed far enough to open the secondaries.
Drivability: The small primaries deliver great throttle response at part-throttle application.
Off Road: The Quadrajet’s centrally-located float is highly resistant to fuel slosh caused by cornering, hill climbing, or acceleration.
As a side note, there was also a model 4M, that used a manually-operated choke. Internally, these three versions were, for all intents and purpose, the same.When discussing Quadrajet models, the number 4 means a four-barrel carburetor. The “M” after that, is a style/model type. Early Rochester four barrels were a “G” series. So, a 4M is a Quadrajet, and a 2M is a two-barrel Dualjet. The next letter, V, C, or E stands for the type of the choke’s thermostatic coil. If there is an E before the number 4, that designates an electronically-controlled carburetor. If it has an M before the 4, that’s a “modified” Quadrajet, built starting in 1975.
Serial Numbers On Products
Carburetors built before mid-1968, have a tag with the part number. In late 1968, the seven-digit part number was stamped vertically into the main housing
First Or Second Generation
All Rochester Quadrajet carburetors are identified by a seven- or eight-digit GM part number. On units made before mid-1968, the part number was stamped around the outside edge of a round metal tag attached to the fuel bowl. Sometime after mid-year 1968, Rochester moved the part number to the flat area near the secondaries, just behind the secondary linkage. The part number of the carburetor will tell you things such as when it was built, and where it originally came from. But, not all Quadrajet carburetors were built by Rochester.
Carter Carburetors was also contracted to build the Quadrajet carburetor for GM cars from 1966 into the late-1970s. So, do not get alarmed if you see a Carter-built Quadrajet with a Rochester part number on it. If you find one with a triangular tag on it, and the standard four-digit Carter part number is followed by an S, that would mean that carburetor was an aftermarket replacement. Any and all replacement parts between Carter and Rochester are directly interchangeable.
Carter Carburetors built Quadrajet carburetors for GM cars from 1966 into the late ’70s.
If the Quadrajet you’re looking at has a seven-digit part number ranging from 702 through 704, these were built before 1976. On these units, the number immediately following these three digits, will designate the actual year of production. After that, you will find either a 2, or a 5. The number 5 designates an emission carburetor from California. The digit following the number 2 (or 5), will indicate the type of GM car it was originally installed. A 4 would mean it is for a Buick, a 5 would mean Oldsmobile, and Pontiac carburetors usually have a 6 or 7.
Chevrolet Quadrajet carburetors would have a 0, 1, or even a 2. The last two remaining digits determine whether the carburetor came from a car equipped with an automatic or manual transmission. Usually an even number will indicate an automatic car, while odd numbers indicate a manual transmission. Carburetors installed on Cadillacs, however, do not follow this rule of thumb. Those carburetors might very well have any of the above model numbers.
Quadrajet carburetors built after 1976, use an eight-digit casting number. These carburetors do not follow the identification numbers of previous years; they will start with either 1705 or 1708. The number 1705 identifies the unit as being built between 1976 and 1979. If your carburetor reads 1708, it was built in the ’80s. While the fourth number denotes the decade, the fifth digit designates the actual year in which it was produced. The last three digits will unfortunately, give you no information about the carburetor, unless you have a Rochester numerical reference chart.
Big Or Even Bigger – 750 Vs. 800 CFM
If your 4M, 4MC, or 4MV Quadrajet was built before 1972, it is a 750 cfm carburetor. After 1972, the CFM rating on all three models was raised to 800. Differentiating a 750 cfm from an 800 cfm casting is easy to do by looking through the primary venturi barrels.
The carburetor on the left has the bulge (arrow), and is an 800 cfm unit. The one on the right does not have the bulge, which makes it a 750 cfm unit.
When looking through the primaries, if you see a pronounced bulge protruding from the side of the wall surface, you have an 800 cfm carburetor. The primary wall of the 750 cfm unit does not have this bulge, and is consistent throughout.
In the early ’80s, GM incorporated electronic connections to the Quadrajet. The Quadrajet’s primary circuit had a small solenoid installed to control the depth of the primary metering rods. These Quadrajets are difficult to modify for conventional use.
From 1975 through 1979, the M4MC was used in GM four-barrel applications, and utilized the standard carburetor-mounted choke and dual choke pull-offs. The M4ME was added in 1976 and is similar to the M4MC, but uses an electric choke. Both of these carburetors can be used as replacement carburetors for the two earlier 4MC and 4MV applications. As a side note, if you’re looking for a M4ME it was also used on 1985 through 1988 Dodge trucks with a 360ci engine.
There are later versions of the Quadrajet that were introduced in 1981, but these were designed to work in conjunction with onboard computers, so we will not get into those. An easy way to determine of you have this E4ME Quadrajet, is the fuel inlet faces straight into the front of the carburetor — instead of connecting at a 90-degree angle — and there will be an electronic connection capability.
Dating Your Carburetor
Most Rochester-built Quadrajet carburetors were given a four-number date stamp. This code can be deciphered as such: the first three numbers are the day of the year (082x = 82nd day of the year) the carburetor was built. The last number is the year (0828 = 82nd day of 1968).
All Quadrajet fuel inlets are in one of two positions. Carburetors intended for Chevrolet, Cadillac, Buick (’67 only), and GMC applications, utilize a fuel inlet that enters the carburetor at a 90-degree angle, facing the passenger's side of the engine. Buick (’68 and newer), Oldsmobile, and Pontiac castings utilize a fuel inlet that is pointing toward the front of the car.
If you are interested in doing some more reading, the Books Rochester Carburetors by Doug Roe, and Haynes Rochester Carburetor Manual by Mike Stubblefield and John Haynes are both very good technical resources for the rebuilding the Quadrajet.
One thing to keep in mind, when trying to date a carburetor, is that the year of production might not always be the same year as indicated by the number on the carburetor. There were an untold number of “replacement” carburetors produced, and it is not unusual to find some with later production dates than what is indicated by the carburetor number.
Chevy Serial Number Search
Throwing another glitch in the program, is the fact that some Carter-built carburetors produced in the late 1960s might have been used on a different model year than the number shown on the carburetor. This was most common in the 1968 and 1969 models, as Rochester was not able to keep up with production.
1957 Chevy Serial Numbers
Finding a compatible donor carburetor for your application should be relatively simple. There are a countless numbers of Quadrajet carburetors still being used, or just waiting for you to rescue them from the local salvage yard. They are a very affordable four-barrel carburetor, and used units can be had for as little as $50 and up. Not only that, but just about every corner auto parts store has a rebuild kit available, depending on the Rochester model you have.
A carburetor with the number 7040205 followed by a Julian date of 0260 would have been built the 26th day of 1970.
Chevy Serial Number Decoder
Hopefully this outline of how to identify a Quadrajet will help you get you car properly restored, or give you the incentive to install one of these over-looked carburetors on your classic Chevy car or truck.