Back in the day when downdraft carburetors first came out, the hot trick was to flip your old updraft intake manifold upside down so you could fit one of the new-fangled downdrafts. On many models the manifolds – which were simpler then – were the same back to front and up and down, or nearly so, so this could be accomplished fairly easily. Once in a while we still see this today. Sometimes this was done much later in the life of the car because the old updraft carb was worn out and no replacement was available. Depending on the engine model, the main drawback would be the loss of exhaust heat for the intake, which would make cold operation more difficult.
Most manufacturers switched to downdraft carburetors around 1932. Chevrolet used a Carter Brass Bowl updraft carburetor up to 1931 and switched to a Carter W-1 downdraft in 1932. These were used through to 1949, when GM came out with it’s own carburetor, the Rochester Model B – shown above on a ‘55 Chevy.
Today, Holley is associated mostly with performance carburetors but in fact Holley carbs have been used on most American car makes at one time or another. In 1957 Holley introduced the modular series of carburetors starting with the Holley 4150 four barrel and 2300 two barrel. These are the ubiquitous Holley 4 barrels that are under muscle car hoods everywhere today and gave rise to Holley’s performance image.
George M. Holley combined a gasoline engine with a bicycle frame in 1896 to make the first American motorcycle, and a year later, at the age of 19, built a 3 wheel car with a carburetor of his own design. Around 1899 George and his brother Earl established the Holley Brothers Company. In 1904 they built the carburetor for the curved-dash Oldsmobile (model H) and by 1906 they were beginning to specialize in carburetors, and soon were supplying large numbers of carbs to Ford. The Ford Model A Holley carburetor holds the record for the most carbs of one kind produced – sixteen million.
The Ford Era
Holley built updraft carburetors for Model T’s (model NH) and Model A’s. In 1938, Holley took over production of the Chandler-Groves two barrel carburetor known variously as the ’94’ (for the venturi area of 0.94 inches, cast into the float bowl of some carbs), AA-1 or later, the model 2100. Many of these have the Ford script on the bowl, but are otherwise the same. These were used on flathead V-8’s and early Y-blocks until 1957, and continued in production in the 2110 version into the 1970s, with the last being the Bugspray version for the VW.
After the war, Holley developed the ‘concentric’ series of carburetors which used a float bowl suspended above the throttle body – hence the nickname of ‘teapot’. The first of these was the unusual side air inlet 885FFC carburetor used on the 49-51 Mercury, followed by the 1901 model in 1952 on Mercury police engines.
Four barrel carburetors started appearing in the early 1950s. Stromberg won the honor of the first four barrel, the model 4A in 1952 on Buicks. Holley followed up in 1953 with the 370 cfm model 2140 concentric carburetor – a four barrel version of the 1901 first used on the 1953 Lincoln. The design was refined in 1955 into the model 4000, another 370 cfm carburetor first used on the new 292 Y-block. Various Fords used Holley 4000s until 1957, the last application being the dual 4 bbl T-Bird set up. By 1957 Holley had a new, cutting edge design in the 4150 modular series, but two of these wouldn’t fit on the manifold in the T-Bird, hence one more year of Teapot use.
However, Teapots (concentric) carburetors continued in production for a long time, with the 2140 being used on International trucks until 1975. Model 1901s were built for use on VW or Porsche engines until the late 70s. Because of the float bowl design, the carburetors work well on severe inclines, which is one of the reasons they were used on various military vehicles.
The 4150 was a radical new design that could be adapted to multiple configurations by changing the combination of float bowls, metering blocks and main bodies. The 2 barrel version is the 2300.
First used on the 1957 312 engine, the 4150 was used on most makes at one time or another and has been adapted into many different versions, including governed versions on trucks. The first models used a vacuum operated diaphragm to open the secondary throttle plates. Mechanical secondary linkages were first used on Chryslers in 1959. Double pumpers with an accelerator pump on both the primary and secondary bores have mechanically operated secondaries and were introduced in 1967 on Chevrolet cars.
The model 4160 is similar but uses a metering plate with fixed metering orifices instead of the 4150’s secondary metering block with removable jets. Both the 4150 and 4160 use the same squarebore flange, which is 5.160″ wide by 5.625″ long on the bolt spacing. The 3160 was an unusual three barrel carburetor
Spreadbore model 4165 and 4175 carbs were introduced in 1971 as replacements for Rochester Quadrajets and other spreadbore flange carburetors (where the secondaries are larger than the primaries). The spreadbore flange is 4.25″ wide by 5.625″ long.
A large race-only version, the 4500 was introduced in 1969 for use in NASCAR.
Modular Carburetors – Stock
The two barrel version, model 2300, was introduced in 1957 on the 272 and 292 engines in cars and trucks, the same year as the 4150 appeared (see above). Model 2300, 4150 and 4160 carburetors were used extensively on passenger vehicles through the 1970s. The model 2300 was used in the factory Six Pack (Mopar) or Tri-Power (Chevy) set ups, with the center carburetor having an idle and choke circuits and a metering block, and the outer carbs being vacuum or mechanically operated secondaries.
Governed versions for medium and heavy trucks were the 2300G, 4150G, 4150MG and 4150EG. 4150EG models were for electronic governors as opposed to the ‘G’ models which were for mechanical (centrifugal) governors.
In the late 70s a new series of modular carburetors were introduced with tighter emissions controls. These were the 2380EG, 4180 and 4180EG and 4190EG. These can be distinguished from other modular carbs because the idle mixture screw are in the throttle body instead of in the metering block. Notably, the 4380 was used on Ford Mustangs and pickup trucks with the 351HO engine in the 1980s, as well as 460 CID engines in motorhomes. Another emissions version was the 4152EG, used until 1990 on GM medium duty trucks with the 366 and 427 CID motors. The 4190EG and the 2380EG were the last carburetors used on US-built trucks, on Ford 370 and 429 truck motors in 1991.
large 2 barrel
large 2 barrel
two barrel version of 4180
improved emissions version of 4150
plates/blocks and other components not interchangeable with other series
improved emissions version of 4180
economy Q-Jet replacement with small secondaries
Flanges (center to center bolt spacing, width X length):
large 2 barrel: 5.125″ X 3.500″
square bore: 5.160″ X 5.625″
spread bore: 4.250″ X 5.625″
Dominator: 5.375″ X 5.375″
Carburetors Derived From the Model 2100 (AA-1, ’94’) Design
Several carburetors came from the basic design of the Chandler-Groves carburetor that Holley began producing for Ford in 1938.
The model 847 was a single barrel downdraft carburetor used on Ford 6 cylinder cars and trucks. The smaller size, 847-F and 847-FS was used on Ford six cylinder passenger cars and trucks (other than cab-over-engine) from 1941 to 1950. The T-847-HGC was a larger version used on the 1948-1950 six cylinder Ford bus and was equipped with a governor.
Model 897 was a still larger version designed for large six cylinder engines such as the 254 cubic inch Ford truck engine.
The AA-1G and 852FFG were governed two barrel versions. They were larger and had heavy duty features like bearings on the throttle shafts and a cast iron airhorn. The two are similar but few parts interchange. These were used on various medium and heavy trucks into the 1970s.
The original AA-1 used a three-bolt flange on the flathead Ford. Later Y-block 2100 models had a conventional four-bolt flange, as did the 2110 models.
Ford COE trucks used an updraft carburetor, the model 859, because an updraft carburetor standing on top the manifold would have been too tall to clear the tilt cab.
The Holley Model 1970 was a carburetor used on farm and industrial applications, notably 3 cylinder Ford tractors.
1900-Series One Barrels
While the 1901 was in the teapot series, the other carbs with this numbering were completely unrelated.
The model 1904 was a brand-new 1 barrel introduced in 1952 on 6 cylinder Fords and used extensively on Ford and IHC six cylinders into the 1960s and Ford industrial applications into the 1970s. The 1904 was notable because it was shorter than previous one barrels, allowing for lower hood lines. An interesting variation was the Visi-Flow carburetor which featured a glass float bowl. The model 1960 was very similar to the 1904 but with an unusual booster venturi insert in the choke plate. The 1908 was very similar to the 1904 except that it had a rectangular choke plate instead of the round one in the 1904 and 1960.
Introduced in 1962, the Holley 1909 was an unrelated, simplified economy model used on smaller 6 cylinder engines by Ford and AMC during the 1960s.
The 1920 was another simplified 1 barrel carburetor introduced in 1960 that was used in various versions on Kasier/Willys Jeeps, a few Chevrolets and primarily Chrysler 6 slant 6 engines into the 1970s. Unlike the earlier 1904, it has an integral throttle body, and consists of two main castings, the main body and the float bowl. This carburetor is unusual in that the entire assembly is made of aluminum, but the main body is treated with an Iridite coating that makes it look green like a chromated zinc bodied carburetor.
The model 1931 was a small 1 bbl with an unusual front fuel inlet in the float bowl; it was used on AMC products.
The 1940 and 1945 were entirely new designs introduced in the late 1960s and used into the 1980s on Ford and Chrysler applications. The model 6145 is a feedback (computer controlled) version used in the 1980s on Ford 4 cylinders and Chrysler Slant 6 engines. After production of 1904s ceased in the 1970s, many Ford industrial engines were equipped with model 1940 carburetors. The main difference between the 1940 and 1945 is in the fuel enrichment system, so they are difficult to distinguish externally.
2200-Series Two Barrels
The first of these was the 2209 used on 1965-1967 AMC and Jeeps, including the 289 V-8. It is a two barrel version of the 1909. The design was revised to form the 2210/2245 series. The 2210 and 2245 differ internally in the power valve system, but are otherwise very similar. These were used mostly on Chrysler products from 1971-1983 and are most commonly found on 360 CID engines and some 400s.
5200-Series Two Barrels
The 5200, 5210 and 5220 were made by Holley under license from Weber (Italy) starting in 1970. These are staged two barrel carburetors where the primary side operates at idle and part throttle and the secondary side opens as the throttle is opened further. Secondary opening is either mechanical or vacuum operated. The 5200 was first built in the US in 1970 for use on the 1971 Pinto. They are marked as Autolite or Motorcraft as well as Holley. This series was used into the mid-1980s on various 4 cylinder engines, including Ford, Chrysler and Chevrolet (notably the Chevette).
The 6510 and 6520 were feedback (computer controlled) versions which incorporated a mixture-control solenoid and were used starting in 1980 on California and in 1981 Federal emissions cars. Non-feedback versions were still used after this in Canada and elsewhere.
Starting in 1949, the Rochester Products Division of General Motors produced carburetors for GM products and other makes as well. The first Rochester carburetor was the AA two barrel used on the new Oldsmobile Rocket V-8 of 1949, followed by the model B one barrel in 1950 on Chevrolets. Model B’s were used from 1950 to 1967 on GM 4 and 6 cylinder applications. They were also sold as replacement carburetors for 1932 and up Chevrolets originally equipped with Carter W-1 or Stromberg BX series carburetors.
Model B carbs are named according to the type of choke they used:
B: manual choke carburetor
BC: automatic choke, choke coil mounted on the side of the carburetor (1950-1962)
BV: automatic choke, choke coil on the intake manifold (1963-1967)
Model B Designs
Internally, there are two main designs: the 1st design with a non-rebuildable leather pump that has a flat stem, used on cars up to 1956 and on trucks up to 1962, and the 2nd design with a rebuildable pump with a rubber cup and a round stem, used on cars from 1957 and on trucks after 1962. To complicate things there have been leather pump kits sold for 2nd design carbs, but still with the round stem. Also, the 2nd design, round stem pumps, come in two different lengths, 2 3/4″ and 2 13/16″. We have both 2nd design pumps available in our kits. Cheaper kits provide just the pump cup. We don’t sell these in our store since the pumps themselves are often worn or damaged – changing the cup won’t help in those cases. Neither will it help if you have one of the non-rebuildable leather replacement cups that were sold at one time.
After two years of production the 1st design carburetors were revised to deal with leaks from the top gasket between the float bowl and airhorn. Starting in 1952, the airhorn casting is heavier and is retained with larger 12-28 Fillister head screws until the end of production in 1967. Today these screws are nearly obsolete, so replacing chewed up old screws has been problematic. To fix this, we’ve introduced a line of master kits with the correct screws and other hard-to-find parts to service all Model B carbs.
Hi, I have a “built” Corvair 180 hp turbo. It has a Crown turbo and no muffler. I’m currently running a Rochester QJet on an Upflow adapter. It runs rich at idle, and has a miserable lean hesitation upon acceleration. It’s a brand new Carter, or Edelbrock QJet clone, or something.
Anyways, it’s WAY too much carb, so I bought an adapter for a WW Stromberg.
What do you reccomend? This is a strictly street driven show car.
As a rule, you do need a lot smaller carb when using a turbo. The WW would probably be in the ball park, but it’s an oddball that it’s hard to get parts for. The issue with pull through turbos is that the vacuum signals are mixed up relative to a naturally aspirated application. At wide open throttle (WOT) in a regular set up, vacuum is low and the power circuit is fully open. With a turbo, vacuum is high at WOT, so that the power circuit closes. That’s why you’ve got a lean hesitation. The power circuit needs to work opposite to that of a non-turbo. The solution is to reference the power circuit to another place in the plenum where vacuum is ‘normal’, which would be after the turbo. This is how it’s done in the Pontiac 301 turbo carb. The vacuum for the power piston is taken not from under the carb, but from after the turbo. It’s actually a little more complicated because the vacuum is modulated by the PEVR – Power Enrichment Valve Regulator, but the point is that manifold vacuum is the opposite of what you would expect for a non-turbo set up.
For the Corvair, you might consider digging up a 301 carb and trying that out. The primary side of the QJet is pretty small, so it might work, as long as you set the linkage up right. One trick is to rig the QJet air valve to only open about halfway, limiting the cfm at WOT.
As an aside, Stromberg WWs were used with some supercharged Studebakers, but this was a blow-through, not pull-through, set up. As long as the entire carb is pressurized, the power system works the same way as on a normally aspirated system. However, the carb either has to be sealed (gas will come out everywhere it’s not) or be in an air box. The Studebaker Golden Hawk used an air box on top of a Stromberg WW carburetor in 1957-58.
The vacuum port on the Pontiac turbo carb that supplies vacuum to the power piston is under the fuel inlet fitting – you can’t see it in the picture. You can tell regular Pontiac 301 QJets from the turbo versions by the extra vacuum port under the fuel inlet. Turbo carbs have three fittings on the front of the throttle body, non-turbos have only two.
Here’s an excerpt from the 1980 New Product Info from Rochester Products Division:
The 4.9 liter Turbocharger V8 application uses a unique power system due to Turbocharger operation. The power system provides extra mixture enrichment for heavy acceleration or high speed operation.
The vacuum power enrichment system consists of a spring-loaded power piston operated by a remote vacuum source. The power piston is controlled by a Power Enrichment Valve which supplies vacuum, according to engine load, to the power piston to position the main metering rods in the jets for sensitive control of air/fuel ratios for power requirements.
The Power System operates as follows:
During part throttle and cruising ranges, engine load is light and vacuum, from the Power Enrichment Valve, is sufficient to hold the power piston down against spring tension and the larger diameter of the metering rod tip is held in the metering jet for leaner mixtures.
As engine load is increased to a point where extra fuel enrichment is required and the intake manifold is pressurized by the exhaust gas driven Turbocharger, the Power Enrichment Valve “switches” and reduces vacuum to the power piston to zero. At this point, spring tension operating on the power piston lifts the main metering rods for increased fuel delivery.
The remote power enrichment feature, through the power enrichment valve, provides richer mixtures during heavy engine loads and wide-open throttle power requirements when the intake manifold is pressurized by the exhaust gas driven Turbocharger at a time when manifold vacuum is high enough tending to operate the power piston in the normally “lean” position. In this way, the power system controls fuel metering during light and heavy power requirements.
The 17080274 carb is the one year where a non-computer controlled carburetor was used on the 301 Turbo in the US. Canadian production used a non-computer carb in 1981 as well, but US cars used an E4ME computer controlled QJet.
We have rebuilding parts for the Pontiac turbo carbs including the electric choke thermostat – a Carburetor Doctor exclusive – available here.
Until 1966 GMC light trucks used mostly GMC engines; after that they shared drive trains with Chevrolet. Medium and heavy duty GMC trucks used their own gasoline engines until 1974.
In the 1960s and 70s these were mostly V6 engines ranging in size from 305 CID to 478 CID; there was also a 503 CID straight 6, a 637 CID V8 and a 702 CID V12. All of the V6 and V12 engines used Stromberg WW or WWC carburetors; the V12 used two of them. We have complete listings of GMC carburetor kits and parts here.
The Stromberg WW-series came in two main variations, the WW and WWC. The WW is the smaller of the two, and is often mistaken for a Carter BBD carburetor. In fact, Stromberg WWs and Carter BBDs were used interchangeably on Mopar applications.
One quick way to tell a WW carburetor is that it has a large accelerator pump lever across the top of the carb. WWC carbs don’t have this lever.
There are many versions of these carbs that look similar, so it’s essential to check the carb number when ordering a kit. The carb number appears on these in a couple of different places. As shown in the pictures, it’s often on a round tag that looks like a washer on the top of the carb. This will usually have the vendor number shown in the table below. Sometimes there is a conventional tag with a GMC number. In many cases there is a ‘Code number’ stamped onto the top part of the carburetor – on the flat area on the float bowl cover.
All WW carburetors use our F77 float, listed here. Unfortunately, there aren’t any new floats for the larger WWC carburetor.
Stromberg WW/WWC Carburetors for 1960-66 GMC Applications
How would a stock 290 hp 350 handle a 650 CFM carb? Would it be to much fuel?
No, the usual size on a stock engine like that is the 625-650 carburetor. (Carter calls it 625, Edelbrock says 650 – same carb). In fact, CFM refers to the maximum Cubic Feet per Minute of air/fuel mixture that a carburetor will flow. In other words, when the engine is operating at high speed at Wide Open Throttle (WOT), how much will the carburetor allow the engine to breathe. So, it is not that too big a carb (too many CFM) will provide too much fuel, rather that it will provide too much air and fuel. Now, if a carburetor provides too much fuel for the amount of air, then it will run too rich, but that’s not caused directly by the carburetor being too big.
As for the common Carter Competition AFBs (made up to 1984 by Carter and sold up to about 1998 made by Weber) and the current Edelbrock AFB, the primary side is the same size in the Carter 625/Edelbrock 650 as in the 500 cfm version so there wouldn’t be any difference in part throttle driveability between the 500 and 625. Maximum air flow for a stock engine like a 290 HP Chevy 350 is less than 500 cfm; if the secondary on the carb was a plain venturi type, you would have to use a small carb. However, on the AFBs there is a velocity valve which limits the secondary air flow so that you can use a slightly larger carb. It allows the 625 carb to work on a range of engine sizes. That’s why Edelbrock sells the 625/650 cfm carb for 350s in general.
By the way, the velocity valve is the counter weighted flapper below the secondary venturi clusters in many AFB carbs. Some, mostly smaller AFBs, didn’t use a velocity valve. The AVS carburetor – both the Carter AVS from the 1960s to the early 1970s and the new Edlebrock Thunder AVS – use a valve above the venturis called an air valve, giving more carefully controlled airflow on the secondary side. This will be for another post.
At The Carburetor Doctor we’ve got a full range of rebuild kits for all Carter AFB carburetors here.
Edelbrock AFBs and Carter Competition AFBs from 400 to 750 cfm use our kit CK294 and F27:
Our CK294 kit features a complete ethanol-resistant Viton accelerator pump assembly (not just the cup!), needles/seats with the solid needle and optional spring-loaded needle for off-road use as well as quality gaskets, instructions and other parts as shown.
I have a 1951 Lincoln, with a 337 Ci Flathead, and am interested in rebuilding the original carb, a Holley 885 FFC
Before I do this, I am interested in knowing the CFM of said carb. It has been suggested that I have a 500-600 cfm for that size of engine, which is 100 % stock
Can you help me out with the CFM.
As far as I know, there aren’t any good published cfm figures for this carburetor. Even if there were, it’s difficult to compare 2 bbl figures to the numbers for common 4 bbl carburetors, since the standard pressure drop for measuring cfm is different for 2 bbls and 4 bbls. So… you can compare 4 bbl numbers to each other, and 2 bbl numbers to each other, but cross comparison is harder.
Having said that, the 885 FFC is about the same size as later model 2300 350-500 cfm Holley 2bbls.
The Holley 885 FFC is the version of the 885 used on 1949-51 Mercury engines and Lincolns. There are other 885s, such as the 885 FFG that was used on trucks for a number of years. More details, along with carb kits and parts are on our site here.
If you’re rebuilding one of these carburetors, you’ll want our kit CK409:
This kit is made in the USA, ethanol-compatible and features hard-to-find parts such as the idle mixture screws and springs, float bumper spring and more. It also includes instructions and an exploded diagram. We also have a detailed factory service manual – CM409.
I have also posted the specification sheets from the Holley carburetor manual for these carburetors on The Old Car Manual Project site.
Welcome to The Carburetor Doctor’s blog about classic carburetors. I’m Rusty, the doctor, and I will be answering questions and posting tech info and interesting stuff about carburetors on this site. Let me know what you think!