does anyone know how to figure the flow characteristics of carbuetors? mainly Winfield SR's size A im looking at buying a pair for on a model-B motor currently im running a pair of stromberg 48's on another B motor but i know some people run 97's and 81's with success the winfields have a base opening of 1.25" where they meet the manifold the design of the winfield doesnt really have any restrictions inside like a stromberg does so im thinking the smaller size might have a similar flow rate as the stromberg with .81 - .97 or 1.03125 venturi's im really in the dark on this issue so any info would be great especially anyone who's really "up" on the winfield carbs the motor will be a flathead of about 7:1 compression with a winfield head larger valves and a higher lift cam then stock(probably winfield su-1a grind) not a full bore racing motor but something pretty hot for the street it will be in a stripped 32 roadster so its not the lightest car in the world but not a tank either anyone have any insight on how these may work or how i can go about comparing them without actually having the carbs they're fairly expensive so i dont want to fork over the money if they're going to be too small and send me looking for a 3rd to try to fit on thanks for any input Zach
thanks Ryan, anything helps, these carbs are over my head as of right now and i cant seem to find any good refrence material on them aside from the catalog that was just on e-bay.....it seemed to have a good deal of information out of my price range though at $400+
You don't want A's. They are the smallest of the small and will just strangle the engine. There's no real fans of the SR's either so its kinda a lose, lose situation with them. Mine are B's. I think they are 1 1/2"? I'm not at home at the moment so I can't check. They would make good runners but would still be under carbed. I've read that Winfield himself said that a 'B' flows 50 cfm LESS than a 97 putting it on par with an 81, however I've seen no proof for that statement yet. I wouldn't run 81's, so there you go! Isn't an 'A' only as big as a stock Zenith up-draft?
thanks clark im not sure on the zenith size seems like i might need 4 of these A's to make a go of things though $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
No fans of the SR? Really? That kind of contradicts a lot of the information out there regarding what cars ran them successfully back in the day, doesn't it?
The only difference between an S and an SR is the SR have a built-in diaphragm style pump. In an updraft situation, this pump will help, but it will not suck enough gas to be used in a downdraft situation, so a fuel pump will be needed. The SR has an adjustment screw to regulate the diaphragm (spelling?) pump so you can turn it down if you don't want to use this. Otherwise, they are identical to the S. In terms of size, the Model A or AA size will be an improvement over the stock Model A Zenith carburetor but certainly isn't going to make the car into a high performance machine. A single B or BB size will help alot and make a noticable difference and will be a pleasant carburetor at all speeds. You don't need to go to doubles or larger sizes unless you are going with an overhead valve head AND you want something just for racing. Anything bigger than a BB will not make for a great "around the town" cruiser. One thing to keep in mind, it that Winfields are designed to be either updraft or downdraft carburetors and the bowls will be marked with the designation UD (updraft) or DD (downdraft) near the size and serial numbers. While you can physically switch the throttle body and float bodies around, a UD bowl will not work on a DD application as it is jetted completely different. You need to be careful in buying these, as original Downdrafts will command a premium price over Updrafts and most downdrafts being sold are not real downdrafts, but an inverted updraft. Also, the size of the bowl needs to match the size of a throttle body, so, if you have a throttle body marked B, the bowl side needs to be marked B as well. Alot of times you'll see a B throttle body with an AA bowl, or a C bowl, or whatever, and this won't work. Strombergs can work great too, but should be jetted for your specific applications if you are using them on a A/B engine.
thanks GZ I've decided to pass on the deal i had cooking for two A sized downdraft SR's they are actually downdrafts im resorting back to a pair of 97's i had saved for the project great info to keep track of though for when i do find a set thanks Zach
yeah, i was looking at those As your talking about (i know you didnt mention which they were, but we think enough alike that i know the ones your looking at! ahahaa). I went threw the same process you did, and also came to the conclusion that i needed 4 if was running As. No sence paying the premium on these ones then eh? at least thats what i thought. But running 4 As would be wild! kind of need a 4 port to make use of it tho. Even then, i would want something bigger tho, cause 4 As on a 4 port OHV probably wouldnt be enough now anyway. Its a never ending struggle! Beecher
I read two articles with a Winfield 6:1 head , B downdraft intake & carb (75mph) and a 7:1 head with "BB" Carb (85mph?) .Old article. Winfield was a pretty sharp man. I'm sure that these combos were great and spot on. I replaced a Burns downdraft and 94 carb with a Winfield downdraft intake and "SR B " carb on my Model B engine. It idles ,and runs better. Top speed is the same at 70mph. I would think 2 "A"s would be fine for your project. May look a little funny with the small "A" choke horns. Send me a PM if you need a copy to adj Winfields or a copy of the Winfield articles.
A couple of thoughts, first most of the people that ran SR's blocked the pump off usually by turning the base as the pumps were not very successful. I do know of a fellow that says his "B" SR seems to run better than his "B". but there again his pump doesn't function. As to the mixing of different sizes of float chambers Winfield service bulletin # 6 recommends using the next size smaller float chamber as a cure for stumbling problems caused by excessive manifold heat.
Bringing an oldie back to the top... How would dual AAs that are siamesed together on a 3 bolt adapter compare to a single Stromberg 97 carb?
Just a fragment: Before airflow measurements were routinely advertised and flow benches spread down to the race engine people, carbs were compared and adverised by venturi area, giving a simple measurable way of comparing carbs. Not as scientific as actual flow measurement but at least something concrete so apples can be compared to apples. Venturi areas are of course not clean, you have nozzle bars and secondar venturis and such to either measure or guesstimate, but at least you have a basis and the parts needing guesswork are a smaller part of the puzzle. You could even decree that Stromberg secondary venturis look about the same in area as Winfield inside-out venturi restriction and bars...
I talked to this guy about my winfields and he seems to know his stuff. I guess he scored a warehouse find of a bunch of winfields and rebuilds them sale. I don't know if the youtube link will work so if not here is his info: ask for Chris @ Brauns Muscle Car & Hot Rod Restorations - (310) 325 - 4303 - [email protected]. www.youtube.com/watch?v=pJbpQ4Dg_oQ
I saw his stuff, but was immediately intimidated when I saw what he was asking for those gold plated things on eBay in the past
My thoughts are it depends on the head you are useing I have a Rutherford overhead and my research showed me that with the large ports on the Rutherford useing two SRs speed up the mixed air passing through the motor giveing better results.
McCulloch Supercharger. Will a dual SR-AA feed a flathead with a McCulloch? Right now a single 97 is doing the job.
Elrod, I feel that a pair of AA's will work for you, but I would opt for a set of B's with the puffer. I had a pair of AA's on my roadster that was model B powered. Most of the Winfield to 3bolt adaptors seemed to be the same adaptor except they drilled for the different Winfield bases. These are wonderful carbs if you set them up . I'm running a set of CC's on my coupe. No problem.
I sent my minions out to chickasha. They snagged me a winfield carb, SAD type, Well almost half B (throttle body) and A (float bowl) I am piecing together parts for a OHV T Hotrod and would like to run 2 A DD Winfield S Carbs. So, Anyone want to do some swapin, or have a core? Mike
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