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Steve Jelf, So KS 
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Joined: 13 Sep 2009
Location: Parkerfield, KS
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 Topic: Model B carburetor?
Posted: 10 Apr 2019 at 8:10am |
The AC books I have don't show or mention this part. What is it? Does it need to be adjusted? If so, how?
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Charlie175
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Posted: 10 Apr 2019 at 8:19am |
That is the Load adjuster. It fine tunes the carb while under a "load" for peak power.
I go to high revs and adjust it both ways until the engines starts to hesitate and then I hit the middle of those setting. I then go up a incline idle down and then open the throttle to see how it responds. It should gain power seamlessly. If not adjust the load again until it does
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Charlie
'48 B, '51 CA, '56 WD45 '61 D17, '63 D12, '65 D10 , '68 One-Ninety XTD
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Brian G. NY
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Posted: 10 Apr 2019 at 9:12am |
The factory carbs had a fixed (non-adjustable) high speed jet. However, these Zenith carbs were used in many other applications which did use the adjustable high speed jet. Not uncommon to find one of those on a B, C or CA. I would consider it a plus as you will be able to "fine-tune" your carb just as Charlie says.
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John426
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Posted: 10 Apr 2019 at 9:52am |
Hi
Do you know how to identify ZENITH model with the label stamp on the carburetor?
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Steve Jelf, So KS
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Posted: 10 Apr 2019 at 10:39am |
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"Do you know how to identify ZENITH model with the label stamp on the carburetor?"
If you mean the aluminum disk, no. It's unreadable.
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mdm1
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Posted: 10 Apr 2019 at 10:47am |
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If it's running good don't touch!
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Everything is impossible until someone does it! WD45-trip loader 1947 c w/woods belly mower, 1939 B, #3 sickle mower 1944 B, 2 1948 G's. Misc other equipment that my wife calls JUNK!
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Brian G. NY
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Posted: 10 Apr 2019 at 10:55am |
I don't know much about Zenith Carbs....all my tractors have M-S Carbs. However.....in the back of my WD/WD-45 service manual, there is a section on both M-S and Zenith carbs including info for other model tractors including the B and C. Here is what little bit of info there is on Zenith series 61 and 161 carbs used on the B and C tractors.
Zenith # A-C Part # Outline # (I don't know what the "outline #" means but it might be part of the number on the tag.) 61AJ7 211955 0-9805 161AJ7 212844 0-9706
The lone cutaway picture shows a carb without an adjustable "main" jet.
Edited by Brian G. NY - 10 Apr 2019 at 11:04am
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Dick L
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Posted: 10 Apr 2019 at 12:06pm |
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All of these carburetors adjust the same way regardless of make. After it is running you set the idle speed where you want it. I personally set my idles as slow as it will run smooth and not hesitate when moving the throttle lever forward. Even if I have to give it a couple notches to move the tractor.
You then go to wide open throttle. You adjust the power jet to get the highest RPM by turning the needle in and up to make sure. The you turn the needle back in until you detect a slight decrease in the RPM's. That will give you the best setting with out placing it on a dyno.
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Brian G. NY
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Posted: 10 Apr 2019 at 1:10pm |
 Dick L wrote:
All of these carburetors adjust the same way regardless of make.on a |
So Dick, are you saying all the Bs and Cs with Zenith carbs have both idle and high speed adjustable jets?
All the manuals say the high speed (power) jet is preset and cannot be adjusted.
You are the resident expert on the little tractors and have seen many more than me but I know I've seen some Bs with no adjustable high speed jet; just a plug there.
Edited by Brian G. NY - 10 Apr 2019 at 1:14pm
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Alvin M
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Posted: 10 Apr 2019 at 2:31pm |
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you can install the adj screw on that carb there is a kit I drill the jet out 003 then you can adj it dont need to take jet out to drill it I do it by hand
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BEK
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Posted: 10 Apr 2019 at 3:30pm |
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I have rebuilt two Zenith carbs. An adjustable jet came with each of the rebuild kits. It is a nice feature as compared to the fixed jet. However, the adjustable jets leak gas. Nothing to freak out about, just the occasional drop. Not a problem when the tractor is not in use and you shut off the fuel and drain or run the carb's float bowl dry.
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Dick L
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Posted: 10 Apr 2019 at 4:30pm |
Brian G. NY wrote:
Dick L wrote:
All of these carburetors adjust the same way regardless of make.on a |
So Dick, are you saying all the Bs and Cs with Zenith carbs have both idle and high speed adjustable jets?
All the manuals say the high speed (power) jet is preset and cannot be adjusted.
You are the resident expert on the little tractors and have seen many more than me but I know I've seen some Bs with no adjustable high speed jet; just a plug there.
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I was looking at his picture only. You can't adjust what you don't have! You adjust the non adjustable with a wire drill bit. sometimes when adjusting a non adjustable jet with a wire drill you get the throw away the jet you just drilled out and start over with a new jet.
Edited by Dick L - 10 Apr 2019 at 4:35pm
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ekjdm14
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Posted: 05 Apr 2025 at 10:41am |
Brilliant info here  , resurrecting this thread as it tells me a lot of what I needed to know about my carb. The illegible AC part number could be "interpreted" as 211955 if you squint just right, the "outline" number looks to be 9805 & there's no adjustable main jet so seems to be pretty much stock.
What I would appreciate, if anyone currently on here knows, is what kind of numbers should one see for "stock" jets for a gas model B.
My engine began life as a 116 Kero model but in it's past has been fitted with a 125 gas rebuild kit, hoping to ascertain whether the carb I have is from/tuned to a gasser also (I believe it would be, but never hurts to check since the manifold is a Kero type & I need carb parts anyway!)
Main jet appears to be stamped 19, the jet in the top half reads 16 and the smaller jet in the base also might be 16 although it's too chewed to be sure. Venturi is a 13.
Most important to my case, the emulsion tube has 45 on one flat & 2 on another. Much appreciate anyone who has a B125 gas carb who could read some of their numbers.
Other than that, for the moment I'm looking for a replacement emulsion tube as I've cracked mine. Got it soldered but ideally want to replace it if I can get one.
Thanks folks.
Edited by ekjdm14 - 05 Apr 2025 at 10:44am
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Stuck Farmer
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55allis
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Posted: 05 Apr 2025 at 8:52pm |
I think mine is very similar… 
Edited by 55allis - 05 Apr 2025 at 8:53pm
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1955 AC WD45 diesel with D262 repower, 1949 AC WD, 1963 A-C D17 series 3
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AveryD12
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Posted: 05 Apr 2025 at 9:34pm |
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The carburetor in the original post looks exactly like the one on my D12 series 3. Don’t know how many different tractors these were used on. From outward appearance it is identical to mine.
Avery
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steve(ill)
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Posted: 06 Apr 2025 at 5:30pm |
a short B carb discussion.......
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Like them all, but love the "B"s.
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steve(ill)
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Posted: 06 Apr 2025 at 5:33pm |
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Like them all, but love the "B"s.
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steve(ill)
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Posted: 06 Apr 2025 at 5:39pm |
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Like them all, but love the "B"s.
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ekjdm14
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Posted: 18 Apr 2025 at 11:10am |
Thanks Steve, missed these replies. Some bedtime reading there :)
Will get a gasket set on it's way at least, might just live with the emulsion tube repair if one doesn't come up over here.
Cheers.
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Stuck Farmer
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