carbking

There is an easy factory fix for this; I have posted it several times on various forums. Jon.

I hadn't jumped in because of insufficient data. What carburetor is being used????? The original carb for a 1958 Buick was Carter AFB 2800s. Factory replacement carburetor is from a 1959 Buick 401, the Carter AFB 2840s. The 401 carb is smaller than the 364 carb. Buick put too large a carb on the 364! It has lean tendencies! They corrected this issue the next year! For either, fast idle (cold) is 1500 RPM, not 1000 as the OP mentioned. Correctly setting the fast idle will make a difference on a cold engine. Idle mixture range is 1/4 turn to 1 3/4 turn. In the FWIW category, unless you have: (A) a racing camshaft, or (B) a totally worn-out engine, 1 1/4 turns is oceans. Assuming you have either of the 2800s or the 2840s, then try adjusting the choke to just touch closed at 65~70 degrees F., reset the idle screws, and reset the fast idle. If a different AFB, good luck. Assuming you have a conventional hot air choke. If electric, then be glad you only have a hesitation, and not a stall. Too many assumptions in this post. Jon.

Both JPS and JAYG are correct about the carburetors. Early two-barrel carburetors were called dual carburetors. When Buick came out with 2 carbs in 1941 they were called compound carburetion. But very common usage for 2 carbs to be called dual carbs; and virtually all early single two-barrels were called dual carbs. The carb in question should be a single Marvel updraft 2-barrel. Jon.

Raggedy Ann - In a different lifetime (well, 50 years ago) Carter made an AVS. It was rated at 630 CFM; but the "new math" changes that into a 650 BUT, EFFECTIVELY, IT ISN'T!!!!! The 630 was broken down as 250 on the primary side, and 380 on the secondary side. Now, the original Buick intake was designed for a Rochester Q-Jet 750 CFM. The Rochester was broken down as 150 on the primary, and 600 on the secondary (if you refer to my first post asking about a square-bore or spread-bore intake). Assuming you have the original intake, then: You have a limitation of 150 on the primary side (from the intake). You have a limitation of 380 on the secondary side (from the carburetor). Adding 150 + 380 = 530 CFM total EFFECTIVE with your carburetor. Of course, if the individual downgrading the carburetor also changed the intake to a square-bore intake, then disregard all of the above except the 630 instead of 650. Your car, your decision, but I think your lady would be much happier if you were to acquire a Rochester Q-Jet somewhere. Jon.

A 12,000 mile carb SHOULD be rebuildable by most enthusiasts. But before throwing rocks at the carb, check the ignition. A perfect carb (well, none of these were perfect ) and an imperfect ignition can run very rich. If the carburetor IS the culprit, best guess would be the vacuum circuit. When the engine is off the vacuum piston will be in the "on" position (all the way up). When the engine is started, vacuum pulls the piston down to the "off" position. An engine that sits unused a lot could have the piston stuck with residue from modern fuel. And paging edinmass - this thing is the modern equivalent of the ancient Johnsons! Jon

Remember, I no longer do carburetors, however: The Ball & Ball single barrel carb (Chrysler design, sublet to Carter for manufacture) has an aluminum throttle body. At least 90 percent of these will need bushing at 60~70K miles! At 100~120K the vacuum circuit in the bowl will need re-machining. At least 50 percent of them will also require a new throttle shaft or building up the old shaft by metal spray, and turning it in a lathe. How many hobbyists have this capability? Easy to check. Use a dial indicator, and measure clearance from throttle shaft to throttle body. Design was 0.004~0.006 inch. An additional 0.003 is acceptable. MEASURE! If the clearance is excessive in the throttle body, the engine will still run fine at cruise, but idle may require bumping upward, and transition from the idle to the off-idle to the main circuit may have a hesitation. Once the vacuum circuit wears, totally unpredictable results. Not a very good carburetor. Before condemning those that are rebuilding for a price; consider what they are doing. The service films are a great result IF the carburetor does not need machine work. Jon.

The idle circuit works because of a negative pressure created by a velocity of air flowing past the edge of the primary throttle plates where the plates meet the throttle body. As the curb idle screw (a.k.a. throttle positioner screw) is turned in, the primary throttle plates rotate open, resulting in a larger opening where the plates meet the throttle body. The larger opening results in lower air velocity. At some point the air velocity is so low what negative pressure created is too low to effect bleedover in the idle circuit. At this point, there will be no discernible difference in idle quality from adjusting the idle mixture screws completely closed; to removing them and placing them in one's pocket. Jon.

JW - if I could clone myself half a dozen times, I still could not do all the rebuilds I turn down! Am trying to sell the shop to someone who has the time to run it, and restore carbs, but so far, no interest. Glad to help with the specs. Jon.

First - we are in Missouri, not California, so not our carb. Having said that, there have been billions and billions of pixels on the internet disturbed when they could have been left sleeping, by someone posting about a vacuum leak at the throttle shaft. IF THERE IS NO VACUUM LEAK AT THE THROTTLE SHAFT, THEN THE THROTTLE SHAFT WILL NOT ROTATE! All carburetors will have a vacuum leak at the throttle shaft! The right way to test is with a dial indicator. Tolerances vary, but the design clearance on the WCFB shafts is 0.004~0.006 inch. In use, wear of 0.003 additional is acceptable. This is built into the calibration by the carburetor manufacturer. So if the clearance does NOT exceed 0.009 measured, then look for issues elsewhere. I have yet to see a WCFB that required bushing the throttle body. I have seen a very few that required replacing the primary throttle shaft. If the throttle shaft IS out of spec; then the only issue would be at idle, and pulling away from a stop sign. These issues can normally be addressed by (A) enrichening the idle mixture SLIGHTLY, and (B) adding 50 RPM to the suggested idle speed. We have had tractor carburetors (the governors beat the throttle shafts to death) come into the shop with the SHAFT WORN HALF AWAY. That is correct; a 5/16 inch shaft was now 5/32 where it moved inside the throttle body. Idle was horrible, but tractors ran great in the field. Jon

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And a bit of further information: Checked the Stromberg database, and the Stromberg engineers suggested a carburetor with a 27.5mm venturi for the 526. The 10184A has a 27mm venturi. Should really run well. Jon

Again, if the tag number is 10184A: Float setting: with body gasket removed, throttle body inverted, and float resting of its own mass on the fuel valve; distance from throttle body to top (actual bottom) of float is 1 5/8 inches. DO NOT BEND FLOAT TO ADJUST!!!!! Change the thickness of the gasket under the fuel valve seat. Preliminary idle mixture setting - 1 1/4 turn from lightly seated Preliminary high speed setting - 1 turn from lightly seated. The adjustment range of the high speed jet adjustment is 0 to a maximum of 2 turns. On the 63 series carburetor, the high speed adjustment modifies the usable diameter of the main metering jet, thus the smaller range than posted for newer carburetors; where the adjustable high speed jet REPLACES the main metering jet. According to Zenith, at two full turns, the point of the needle should not be effecting the fuel flow of the main metering jet; in other words, the jet is at full flow. Again - these adjustments are for carb 10184A, and should NOT be taken as general adjustments for other Zenith carburetors. If the engine was running well, the high speed adjustment should probably be returned to its existing setting. If you need it, we offer a 100 % made in USA repair kit for this unit. Jon

Hard to read the tag. IF THE TAG READS 10184A then: (1) type 63 (2) accelerator pump, and power valve acculator (3) adjustments - yes, circuit - no. Jon.

Agree with Essex. Some year from 1924 through 1928. Wrong bowl cover, so impossible to determine exactly which year Essex without total disassembly of the carburetor. Jon.

I am reminded of the Wilt Chamberlain / VW commercial...................... Jon.

Import - lightened 1968 Datsun SRL-311 with factory race motor. Domestic - 1974 Pontiac GTO with highly modified Pontiac 350, and lightened chassis Non-qualifiers. Import - Jaguar XK-120-M, Jaguar XK-140, Austin-Healey 3000 Domestic - 1963 Corvette 327/340, 1968 Mustang with Shelby engine, early Dodge Hemi Today, mini-van; but there are memories. Taught my wife to drive a 4-speed in the Corvette. And in the interest of total disclosure, ALL of the above would run 70 MPH. Jon.

That is indeed a Stewart model 30. The BB1D is too large. Jon.

Air Friction. One of the "my dog is bigger than your dog" aftermarket carburetor companies. Jon.

It would be a LOT EASIER if the intake were an Offy aluminum 2x4 with 2 genuine Carter AFB carbs Reinstalling that cast iron intake requires 5 individuals: 2 on each side to lower the intake onto the heads/block, and 1 to make sure everything is aligned. Jon.

Intake manifold weight is just a little shy of 2 tons Very easy to let it slip just enough to mis-align the cork gasket at the rear of the block. Don't ask me how I know! Jon.

OK - again will attempt to post without arousing anyone's ire. When choosing a replacement carburetor, there are several IMPORTANT issues to address (cost is the very LAST one). (1) The carburetor needs to fit the manifold (or an adapter fabricated). This is generally done by measuring the center to center bolt spacing of the manifold. (2) The INTERNAL VENTURI size needs to match the engine for air flow PLEASE look at this article on Stromberg SF series carburetors: Stromberg SF carburetors Please note that even the smallest (the SF-1) has FIVE DIFFERENT INTERNAL VENTURII so it may be used on engines from 130 ~ 260 CID. One size does NOT fit all. (3) The type of driving one does is very important. THE NEW ZENITH CARBURETORS HAVE NO POWER CIRCUITS (well, at least the cheap versions do not). Thus even if the venturi is properly selected, and the engine purrs like a kitten on level terrain, the engine might be a "gutless wonder" when climbing hills. To explain the importance of the power circuit, will use an example of the 1956 Chevrolet with 283 CID, and a Rochester two-barrel carb. The Rochester two-barrel is one of the easiest carburetors to understand that has even been built! The main metering circuit (for normal driving) has two jets of diameter 0.052 inch (it is a two barrel, one jet for each barrel). But when the driver puts his/her foot on the floor and activates the power circuit, FOUR additional 0.055 inch jets come into play. So the power circuit ADDS more than twice the fuel of the normal main metering circuit to the total fuel being supplied. (4) For an updraft carburetor, it is important to know if the fuel system is gravity feed or pressure feed. THE SAME CARBURETOR (MODIFIED) MAY BE USED FOR EITHER, BUT NEVER BOTH. (5) Cost. Larger carburetors will be more expensive than smaller ones. Carburetors with accelerator pumps and/or power circuits will be more expensive than those without. (6) Finally, when one changes from the original factory equipment one becomes one's own engineer. Do it right, and a large percentage of older cars THAT ARE DRIVEN may be improved with a well-researched aftermarket carburetor. But go back and read the comments by John Ruskin before buying the cheapest unit available. And Dave, the throttle bore is really not very useful by itself, as it normally is a function of the center to center spacing. The critical measurement is the smallest diameter of the internal venturi. Jon.

Nice pictures! A bit of clarification might be useful. Your pictures show the "227" stamped in the underside of the throttle body. This is the "code" number. Your pictures also show "1-227) on the lower flange of the throttle body. This is NOT the code number. This is the "blank" casting for the throttle body. Occasionally, as in this case, the number following the "1" will be the same as the code number, but certainly not always. Also, the metering rods sometimes are used on more than one carburetor, and of course, they may be easily changed. But the combination of the two will generally get one close on the identification. Jon.

Peter - it would be a Stewart Model 30. Jon.

Occasionally, someone wishes to change out a carburetor; and there is a lot of misinformation regarding carburetor sizes, and what might be the best size carburetor to use. I have always believed, that everything else equal, one should look at the work of the original engineers. I did this article primarily for folks on a hot rod forum, but the information might be useful for those considering changing out an original carburetor from maybe a mid-50's Buick, or ??? to one of the new imitation carburetors, and the size one might choose. My thoughts are that if the vehicle originally came with a carburetor the quality of the WCFB, and the engine is basically stock; then the best carburetor would be the original. Anyway, for what it is worth: WCFB flow ratings Jon.

David - both the Stewart and the Penberthy I mentioned in my first post have the centerline of the carburetor the same as the centerline of the car, rather than perpendicular as yours is installed. Jon.