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Technical WCFB carburetors

Discussion in 'The Hokey Ass Message Board' started by tubman, May 11, 2020.

  1. tubman
    Joined: May 16, 2007
    Posts: 6,913

    tubman
    ALLIANCE MEMBER

    I have a '51 Ods with an old Offenhauser dual quad manifold. It is for the old "Square-Bore'" carbs. I have one WCFB from a '54 Chrysler New Yorker that fits the manifold and am looking for the second carb. There are a couple prospects on eBay now (the prices are not outrageous), but they are for '55 Chryslers. Since both are 331, does anyone know if they are close enough to be used as a pair? I would think so, and at a reasonable price, I would probably just grab one, but for over $100 for a core, I thought I'd check first.
     
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  2. I've got several that are original and several that are rebuilt, Some have tags and some don't. I can get pix tomorrow
     
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  3. Roothawg
    Joined: Mar 14, 2001
    Posts: 24,522

    Roothawg
    Member

    I think the dual quad carbs are different. I have to find a set for my Caddy intake as well.
     
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  4. I think the difference is one carb doesn't have a choke on it. I have 2 sets on a dodge 2X4 manifold I' get some pix,
     
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  5. Dbhsvr
    Joined: Jan 12, 2020
    Posts: 13

    Dbhsvr

    Am working on a set of wcfb’s for my 57 chevy dual quads. My numbers are no right for originals, but seem to be a matched set for single 4bls. After lots of research i can clone them to very close. Right now i need a set of correct metering rods to replace the ones in them, jets are correct but need the metering rods to match the jets. Bought an online manual, that pretty much covers most versions of wcfb’s with specs. 347 pages for $10 has been very valuble
     
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  6. tubman
    Joined: May 16, 2007
    Posts: 6,913

    tubman
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    I'm sure I can handle the metering rods/jets/choke problems. I just want to know if the '55 carb is close enough to the '54 to use (if anyone knows) before I spend more than I want to.

    I do realize that finding a matched set of dual quads from a 300 is impossible (or impossibly expensive).
     
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  7. carbking
    Joined: Dec 20, 2008
    Posts: 3,715

    carbking
    Member

    Carter made a lot of different WCFB carburetors (I have 300 listed in my database).

    As a general rule, carburetors for a factory dual quad application would be internally smaller (main venturii) than a single carburetor for the same engine.

    As another general rule; unless one is just shot with luck, or has an extensive carburetor background AND a machine shop, the least expensive dual quads that really work well, would be the factory set.

    But, to answer your question, there are major internal construction differences going from the 1954 Chrysler WCFB to the 1955 Chrysler WCFB.

    Chokes were mentioned in the thread. Many dual quads for luxury vehicles used chokes on both carbs (better driveability). Unless the customer demands no choke, I use chokes on both carbs on any aftermarket setup, including my own.

    One other comment: if one is going to use larger than factory carburetors on a dual quad, best NOT to try using the factory dual quad calibrations (rods, jets, etc.). The lower air velocity on the larger carbs will cause the engine to run incredibly lean...........not a good thing. If the larger carbs are used, best to initially build them absolutely stock for a repeatable base line, then tune from there.

    The 1951 Olds has an engine of 304 CID displacement. If I were going to suggest dual WCFB's for this engine (assuming mostly street, and no serious racing), I would suggest looking at the WCFB's from MoPar 270 CID or 277 CID to see if they would fit the manifold. Alternately, another possibility might be the Holley's from a 1954 Mercury 254. I don't mention the Chevrolet 265 or 283 as an alternative, as the Chevy engines vis-a-vis the Olds engines have a totally different fuel curve. MAJOR recalibration would be necessary (on second thought, these would be a great idea, as I know a hillbilly that can supply ALL of the necessary recalibration rods, jets, springs, etc. at a price ;) )

    A well-engineered set of dual quads on a V-8 will cause the owner to throw rocks at any tripower (other than a tripower on a 6 cylinder); but one that is built on whats available without doing the engineering can run just as bad as the tripower! Mathematics and physics are your friends!

    Jon.
     
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  8. Who would have thought there are so many combinations, a lot of good information. Thanks
     
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  9. tubman
    Joined: May 16, 2007
    Posts: 6,913

    tubman
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    Thanks, Jon, that's the information I was looking for; no '55 for me! Unfortunately, the only other manifold I have for it is an old Offy triple.:( I guess I'll just keep lookin' for a matched set of something. I believe from what you're saying (and what I've read from your other posts) that the only worse alternatives would be anything that required adapters, so it looks like I'm stuck with WCFB's, early 4G's, "Teapots", or maybe even a couple of old Strombergs. Good luck on finding a matched set of anything. It looks like my chances of finding a matched pair of anything else is a lot less than finding another '54 carb, so I'll just keep looking. If I find one, I'll rebuild it stock and start from there.

    If worse comes to worse, I can always run small base 2G's on the Offy and block off the end carbs in order to get on the road and worry about performance later.
     
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  10. jimmy six
    Joined: Mar 21, 2006
    Posts: 14,795

    jimmy six
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    Mine are '53 Olds. Bought at different times starting 6 years ago with the same tag numbers. Engine is a 296" with slightly higher compression than the Olds in 53. One was in a factory box and I'm guessing a dealer take off for warrentee work. Best one I bought as it is my lead carb. I run only the choke on that carb with the front one set full open. Front barrels have the brass crossover breathers like the 245-270 Chevrolets. The rear barrels don't have the tubes to slide into. I tried one size smaller main jets on the lead carb but it did not like it so I put in the stock ones. Other than a choke arm both are the same.

    I can tell you after 5 years this engine and set up works perfectly like it was made for the engine. I idle on both set with a UniSyn when first installed and checked 3 years later. When cold I push the foot feed to the floor to not only set the choke which is only 1/4 on enough to put the fast idle on the rear carb on the 1st setting, but to squirt fuel at the front cylinders. As the pictures show I run progressive linkage something Ford E codes did not. Good Hunting 8D3812AD-A2D0-41BF-B53D-B5C8E57364A1.jpeg 8B9875CB-B5FB-4312-A832-C187472E4A9C.jpeg
     
    Last edited: May 12, 2020
  11. Dbhsvr
    Joined: Jan 12, 2020
    Posts: 13

    Dbhsvr

    Jimmysix, what air cleaners are you using? They kinda look like corvette but i dont see any loovers
     
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  12. jimmy six
    Joined: Mar 21, 2006
    Posts: 14,795

    jimmy six
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    Tops are from a kitchen supply warehouse, pan lids I had polished. Filters are Empi, aftermarket for VW’s and the bottoms are from Charlie Price’s Vintage Speed for the small top 4 barrel ......way to much $$$$$ into them. All thread mount screws are offset so they clear each other..
     
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  13. Dbhsvr
    Joined: Jan 12, 2020
    Posts: 13

    Dbhsvr

    Thanks Jimmy, very cool.
     
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  14. Roothawg
    Joined: Mar 14, 2001
    Posts: 24,522

    Roothawg
    Member

    Carbking, what would you suggest for a 396 CID Cadillac? I have an aftermarket, small footprint intake for WCFB.
     
  15. carbking
    Joined: Dec 20, 2008
    Posts: 3,715

    carbking
    Member

    For:

    Vintage racing
    Street performance
    Or basically eye candy

    ???

    Jon
     
  16. Roothawg
    Joined: Mar 14, 2001
    Posts: 24,522

    Roothawg
    Member

    All around drivability on the street. The motor will have a few go fast parts in it, but the main objective is reliability.
     
  17. tubman
    Joined: May 16, 2007
    Posts: 6,913

    tubman
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    Thank you "jimmy six" you have given me hope.:):)
     
  18. carbking
    Joined: Dec 20, 2008
    Posts: 3,715

    carbking
    Member

    First thoughts suggest the Stromberg type 4A carburetors used on the 1952~1954 Buick 322 CID engines. There was a different one used each year. They are identified by a STAMPED number on the air horn (7-??). Of course, the 1954 would probably be the best; but "best" is only a small percentage of a per cent.

    1952 - 7-92
    1953 - 7-94
    1954 - 7-98

    These carbs are some of the most reliable carbs ever produced. Parts availability may be limited to fewer vendors than the WCFB, but parts ARE readily available.

    Jon.
     
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  19. Dbhsvr
    Joined: Jan 12, 2020
    Posts: 13

    Dbhsvr

    Carbking, something you said earlier a few posts back has me questioning what i thought i needed, heres the setup, dual wcfb's to go on stock '57 283, stock manifold think stock 245-270hp Corvette. My tops are both 1271's, bowls are 1108's, bottoms are 1386B's. This setup is new to me. These are jetted with .093 primary's, .053 secondary's, and 302S idle jets just like original '57 corvette 2x4 wcfb's that have a slightly smaller main venturi. The jets call for 1350 metering rods but mine have 1349's which appear to be slightly smaller. You talked about the larger venturi's making for a lean condition, will my smaller metering rods counter the lean condition that might be caused by the larger venturi's? I was thinking i needed to change the metering rods to the larger 1350's but maybe not. Or am I just out in the weeds beating myself over thinking this. Thanks, didn't mean to hijack this thread.
     
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  20. lippy
    Joined: Sep 27, 2006
    Posts: 6,825

    lippy
    Member
    from Ks

    Are the jet numbers different than say Holley jets? .093 would be a huge Holley jet. Lippy
     
  21. carbking
    Joined: Dec 20, 2008
    Posts: 3,715

    carbking
    Member

    Dbhsvr - without knowing the identification numbers of the carburetors (WCFB's cannot be positively identified from the casting numbers) we are basically guessing.

    Lippy - Carter primary jets will generally be larger than Holley jets for the same size carburetor, as Carter used metering rods. The effective metering area on the primary side is the area of the jet less the dynamic area of the rod depending on the vacuum at any given value of vacuum.

    EDIT: who said a picture is worth a 1000 words?

    This is an illustration from one of the Carter Carburetor school lectures where the subject was the operation of the venturi. This test was performed by students in the laboratory. Note there are open glasses of water with tubes inserted into the water and the other end of the tube at right angles to various components of the venturi. The shaded area in the tubes just above the water level in the glasses indicate the water head developed by the negative pressure in the tubes created by the air velocity through the venturi. If the large venturi size is increased (larger carburetor), the air velocity at any given RPM is decreased, reducing the water head at each point, and reducing the amount of fuel which would be pulled into the venturi (consider the tubes as fuel nozzles) at all points. Thus the engine would be lean. One can compensate for this condition if the size of the larger carburetor is not TOO great by calibrations.

    [​IMG]

    Jon.
     
    Last edited: Nov 14, 2020
  22. carbking
    Joined: Dec 20, 2008
    Posts: 3,715

    carbking
    Member

    Referencing the post above:

    Jetting calibrations are not the only method of recalibrating a carburetor.

    When Holley issued the dual quads for the 1956 Ford, Holley knew the castings (internal venturi size) of the standard 4000 was too large for a dual installation. They also knew this installation would have minimum sales, and didn't really wish to retool the main casting. The solution was to place spacers on the booster venturi rings, thereby effectively reducing the size of the venturi, and increasing the venturi air velocity.

    Pictured are the venturi booster from the Holly R-1161 (normal production) carburetor (the ones with the split pin reducers) and the booster from the R-1268 (dual quad production) with the brass rings, and the lower portion of the booster spun over the spacer.

    [​IMG]

    Jon.
     
  23. jimmy six
    Joined: Mar 21, 2006
    Posts: 14,795

    jimmy six
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    ^^^^^ very interesting. Would this have been the norm for factory carbs in a multiple application when the it did not use a progressive system? Ford dual quad up to 57 were straight linkage and the 427 style was progressive. I believe the Cadillac also was straight but the Chevrolet’s were progressive. Mopars with cross rams for sure were straight.

    Just making me think how well the dual quad system works on my Y-Block using the 1953 Oldsmobile Carter WCFB’s which were designed as singles and I’m using them progressive. My plugs always look good and my mileage stayed the same as when I used a single factory Holley or WCFB with a distributor change to eliminate the Loadmatic feature.

    Thanks Carbking...
     
  24. Dbhsvr
    Joined: Jan 12, 2020
    Posts: 13

    Dbhsvr

    Thanks for the help Jon, i have no clue what these carb originally were, chasing the numbers of the parts i suspect they were 2505S, 2555S or 2655S Chev carbs of the ‘57 vintage. I‘m just guessing, no way to really know.
     
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