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The Carter W-1 as used on Chevrolet


General information


Chevrolet used various versions of the Carter W-1 as original equipment from 1932 through 1949. In addition to the original equipment (O.E.) carbs, other units were offered as replacements; as Carter continued to improve the performance and reliability of the W-1. However, do not believe that all W-1 Carters were used on Chevrolet; as 128 different W-1 carburetors were built. These various units were used on Auburn, Cadillac, Essex, Federal, Frazer, G.M.C., I.H.C., Hudson, Hupmobile, Kaiser, Oldsmobile, Plymouth, Pontiac, Reo, Studebacker, and Terraplane in addition to Chevrolet.


Chevrolet produced W-1 carburetors  - picture


Chevrolet produced many of the carburetors in their Bay City plant. These Chevrolet-produced carburetors may be identified by a large cast “C” on the cast iron body, and the Chevrolet part number on the tag instead of the conventional Carter number.


1932 Chevrolet  picture side   picture front   picture back


Early production unit on passenger vehicles was 212s (Chevrolet 836615), followed in mid-year by the 235s (Chevrolet 836853). The 222s (Chevrolet 836735) with a smaller venturi was used on trucks. The carburetor pictured is the 222s truck carburetor. One can see the cast “T” on both the front and back views. This unit is a Chevrolet produced unit, so the cast “C” is also visable. These were among Carter’s first downdraft carburetors (the 1931 U-1 and W-2) were earlier. As such, these are basically an updraft design built on a downdraft frame. They are scarce, expensive, and problematic. We suggest using these units ONLY on number-matching showcars, not on “drivers”. These carburetors have the following characteristics (to aid in identification if the tag is missing):


Bottom stamp (if still present) 212s – 77; 222s – 81; 235s – 89

High idle mixture screw

2-hole bowl cover

2-hole airhorn

No distributor vacuum port


1933 Chevrolet – picture side   picture front


The Chevrolet model CA used the Carter 259s (Chevrolet 837110). The Chevrolet “Standard” used the Carter 260s (Chevrolet 473685). The carburetor for the “Standard” had reduced airflow. These units are basically calibration changes to the 1932 units. They are scarce, expensive, and problematic. We suggest using these units ONLY on number-matching showcars, not on “drivers”. These carburetors have the following characteristics (to aid in identification if the tag is missing):


Bottom stamp (if still present): 259s – 03; 260s – 13

High idle mixture screw

2-hole bowl cover

2-hole airhorn

Distributor vacuum port


1934 Chevrolet – picture side   picture front


The W-1 carburetors for 1934 received the first major design change, that of moving the idle mixture control screw from the top of the idle circuit in 1932 and 1933, to the lower part of the throttle body. This resulted in a much-improved idle circuit, thus improving the driveability, if not the overall reliability of the unit. Carburetors used in 1934 were the 284s (Chevrolet 837341) on the Master and the 285s (Chevrolet 837373) on the Standard. Again, the carburetor for the Standard has less airflow capability. While the driveability of these units is much improved over the 1933, they are scarce, expensive, and problematic. We suggest using these units ONLY on number-matching showcars, not on “drivers”. These carburetors have the following characteristics (to aid in identification if the tag is missing):


Bottom stamp (if still present): 284s – 220; 285s – 221

Low idle screw

2-hole bowl cover

2-hole airhorn


1935 Chevrolet


The 284s from 1934 was held over and used on early production 1935 Master cars. This unit was superceded in late 1935 by the 319s (Chevrolet 837894). The Fleet cars used Carter number 321s (Chevrolet 837918). The 321s (fleet) retained the 2-hole airhorn, but the 319s incorporated a design change to a 3-hole airhorn. This new design minimized warpage of the airhorn, and premature wear and failure of the choke shaft. While the reliability of the 319s is  improved over the 1934 units; they are still scarce, expensive, and problematic. We suggest using these units ONLY on number-matching showcars, not on “drivers”. These carburetors have the following characteristics (to aid in identification if the tag is missing):




Bottom stamp (if still present): 319s - 265

Low idle screw

2-hole bowl cover

3-hole airhorn




Bottom stamp (if still present): 267

Low idle screw

2-hole bowl cover

2-hole airhorn


1936 Chevrolet


The 319s introduced in mid-1935 was also used in early 1936; and superceded in mid-1936 by 334s (Chevrolet 838013) on the Master. The Fleet vehicles used 335s (Chevrolet 838047). The major difference between the 319s and the 334s was calibration. A new metering rod with a different profile was introduced on 334s with a different midrange and power step. However, this proved to move the curve too far, and this rod was superceded by another rod that was retrofitted on the 319s. These units are scarce, expensive, and problematic. We suggest using these units ONLY on number-matching showcars, not on “drivers”. These carburetors have the following characteristics (to aid in identification if the tag is missing):


Bottom stamp (if still present): 334s – 265; 335s – 279

Low idle screw

2-hole bowl cover

3-hole airhorn


1937 Chevrolet – picture 346s


1937 marked the introduction of the 4-hole bowl cover. This corrected the next-to-the-last major design flaw in the W-1. Carter recognized that the pressure exerted by the pump return spring caused the 2-hole bowl cover to warp profusely, and corrected the problem. While other problems still exist, the 1937 carburetors, when properly restored, have decent performance and are fairly reliable. This is the first year W-1 that we can recommend using on daily drivers as well as number-matching showcars. However, the carburetors are still scarce and expensive. 346s (Chevrolet 838526) was used on the Master, and 358s (Chevrolet 595959) was used on the Fleet vehicles. All W-1’s from this date forward have low idle screws, 4-hole bowl covers, and 3-hole airhorns. These carburetors have the following characteristics (to aid in identification if the tag is missing):


Bottom stamp (if still present): 346s – 292; 358s – 305

Throttle arm has three bends (previous units had none)

Two-piece choker valve


1938 Chevrolet – picture 391s


The 1937 Fleet 358s was retained for 1938. The carburetor used on the Master was 391s (Chevrolet 838682). The 391s differs from the 346s primarily in the use of the 1-piece choker valve replacing the 2-piece, and a change in the relief on the choker spring (now external instead of internal). The stamp number for the 391s (if still present) is 337.


1939 Chevrolet – picture 420s


Two new carburetors were introduced in 1939. The 420s (Chevrolet 838938) was used on the Master, and 434s (Chevrolet 838990) was used on the Fleet vehicles. These carburetors differ from the 1938 versions primarily in the design of the throttle shaft. The 420s has only 2 bends on the throttle arm rather than three. The 434s still has three bends, but they differ from the 1938 Fleet unit. Bottom stamps (if still present): 420s – 365; 434s – 373.


1940 Chevrolet


Both of the 1939 carburetors (420s Master, and 434s Fleet) were held over for the 1940 model year.


1941 Chevrolet – picture 483s


Another major design change was introduced in 1941. This change involved the counterarm used to control the pump and the metering rod. All previous W-1 carburetors used a steel arm affixed to a brass countershaft. The countershaft rotated in a hole drilled in the “tower” of the bowl cover. This was the last major reliabiltiy problem with the W-1. For 1941, a fixed stub steel shaft was inserted into the hole in the tower, and the steel counterarm rotated on the stub shaft. Now we have steel rotating on steel, rather than brass rotating in zinc alloy. Another change implemented in 1941 was the 1-piece accelerator pump. Previous pumps had been rebuildable, with a threaded round brass shaft and a nut, washer, and thimble that held a replaceable leather cup. The new accelerator pump used a flat steel shaft and is not rebuildable (well, by conventional means anyway). The 483s (Chevrolet 839500) was used on the Master, and 492s (Chevrolet 839534) was used on the Fleet vehicles. Flange stamp numbers, if still present: 483s – 421; 492s – 432.


1942 Chevrolet


Carter documentation indicates that the 1941 carburetors were also used on 1942 models.


1946 Chevrolet – picture 574s


574s (Chevrolet 839987) was used on the Master in 1946. This carburetor is virtually identical to 483s, differing only in a slight casting change and later production models using a different countershaft. All parts are interchangable with the 483s. The 492s Fleet carburetor from 1942 was retained. Flange stamps on the 574s are the same as the 483s. A new Fleet “economy” carburetor 616s (Chevrolet 3835156) is introduced. Flange stamp on the 616s is 432


1947 Chevrolet


The 574s, 492s and 616s from 1946 are retained.


1948 Chevrolet


The 574s, 492s and 616s from 1947 are retained.


1949 Chevrolet – picture 684s


684s (Chevrolet 3688154) was introduced on the Master. Carter does not specify any fleet carburetors for this year. The 684s differs from the 574s primarily in that a flat steel rod has been added connecting the choke arm and the throttle arm. This rod causes the throttle to be opened slightly when the choke is engaged, thus acting as a fast idle. Another change was made to the accelerator pump circuit, placing the pump return spring on top of the pump rather than beneath it. Many parts for the 684s are virtually unique to the 684s, making this unit one of the most expensive of all W-1’s to restore.


Restoration of the Carter W-1


As with the restoration of any carburetor, some homework PRIOR to disassembly of the carburetor is in order. This article should aid in the identification of the carburetor in question. Acquire good instructions (a Chevrolet Shop Manual, or both the parts and service pages from a Carter Master Manual) AND READ THEM! Now carefully disassemble the carburetor. If you are unsure of your ability, try mounting a camcorder on a tripod, direct the camcorder at your work, and talk to the camcorder. Now you have a reference when reassembling the carburetor.


Acquire the PROPER kit. While many parts will physically interchange from carburetor to carburetor, they may not correctly function. For this reason, we offer EIGHT DIFFERENT repair kits for the O.E. Chevrolet W-1 carburetors. If you really believe “one size fits all”; try walking a mile in your spouse’s shoes.


Carter printed often that the low speed jet in a W-1 should never be reused. This was good advice for the “parts replacer”; however the jet MAY be reused with some reworking. The reason that Carter suggested not to reuse the low speed jet is that the upper end of the low speed jet tube is inserted into a tapered passage. As the jet is tightened, the taper of the passage forms the upper seal for the jet. If one simply reuses the jet, the seal may not be perfect, resulting in a poor idle condition. However, one may CAREFULLY enlarge the upper diameter of the used tube by inserting a tapered object into the upper end (an icepick works). Thus the tapered passage will form a seal with the enlarged diameter.


In restoration, there are a number of “problem” areas to inspect. These are as follows:


Airhorn warpage (2-hole airhorns)

Bowl cover warpage (2-hole bowl covers)

Worn countershaft an/or countershaft hole (1940 and earlier units)

Pump/metering rod linkage for elongated holes and worn rod tips (ALL)


Warpage of either the bowl cover casting or airhorn casting should be done SLOWLY with heat and pressure. DO NOT FILE, MILL, OR OTHERWISE REMOVE METAL IN AN ATTEMPT TO FLATTEN THESE CASTINGS. DO NOT USE ANY SEALERS TO ATTEMPT TO FILL THE CAVITIES.


Worn countershafts should either be replaced, or built back to standard if the restorer has a “metal-spray” capability. Solder will NOT work!


Worn countershaft holes may be repaired by fabricating a holding fixture for plumb, and installing a bronze or brass bushing.


Worn steel arms and rods should be replaced (they are readily available at this time).


There has been much discussion on the internet concerning the use of neopreme fuel valves and deathanol. While deathanol creates many problems for the restorer, the problem with the newer fuel valves lies in an “economy” move by the manufacturer. The “staking” process has been eliminated. The effects of this process may be duplicated by the restorer. Prior to installing a new neopreme fuel valve, acquire the following: small  wooden block, steel ball from a modern Q-Jet, drift punch, and a hammer. Set the thread of the fuel valve seat on the wooden block, insert the ball inside the seat (replacing the plunger), set the drift punch on top of the ball, and whack the drift punch with the hammer. The wooden block protects the threads from damage. The pressure from the steel ball will form a chamfer around the orifice, eliminating the sharp edges which cut into the neopreme, and providing a larger area for a better seal.


For those who would like to see original Carter service instructions, we have (WITH WRITTEN AUTHORITY FROM CARTER CARBURETOR COMPANY) included a PDF copy. Carter W1 service instructions


Other Chevrolet W-1’s


I have not included either the replacement W-1’s or the military W-1’s in this article. Touching on the replacement units, the most common replacement is 569s, which is basically a 483s/574s body with 1932~1936 throttle arm, choke arm, and calibration. These make excellent replacements for the 1932~1936 “daily driver”.


Other uses (multiple carb set-ups)


The W-1 utilizes a mechanical power system. For this reason, they are much easier to tune on “aftermarket” multiple carb set-ups than those carburetors with a vacuum power system (have you ever tried to hand-wind a power piston spring?). The 483s/574s units are readily available, inexpensive, and parts are readily available; plus when restored, they are virtually bulletproof. The 684s fits this description except for the parts, but is not necessarily recommended (except possibly the center carb of a high dollar 3 carb unit) because of the parts availability and price.