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1950 B Zentih B23 Carb 10698A Question |
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SC_MudDuck
Bronze Level Joined: 24 May 2020 Location: Mullins, SC Points: 41 |
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Posted: 24 May 2020 at 6:32pm |
Hello friends, long time reader, new to the forum and new to the AC B and tractors in general.
I have lots of questions, but will start here. Recently got a B from a family member. It ran decent, but had sat around for some time. When I got it, it was running until it didn’t. So, I decided to rebuild the carb with a complete kit, chose not to change out the choke lever, but replaced the throttle lever. Soaked it in Gunk Carb cleaner, followed by degreaser rinse , and then a water rinse before blowing it out with carb cleaner aerosol and compressed air. Rebuild went well and got it all back together. Reinstalled onto the tractor, fired right up, first time and every time since. The problem is that doesn’t run well. I try to adjust the 3 external adjustments but no difference in the way it runs. It seems to be running extremely rich and surges when driving. I decided to pull the screw that covers the main jet while it was running to make a live adjustment, and low and behold no black smoke and smooth idle when I cracked the main cover open. The more it opened the better it ran. No fuel came out until I shut it off and then it poured. So, it seems to me that the carb is starved for air. Is this a good assessment? Sorry if this has been addressed previously, but I haven’t been able to find it in the search. |
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SC_MudDuck
Bronze Level Joined: 24 May 2020 Location: Mullins, SC Points: 41 |
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Please let me know if issues unclear. I would really appreciate some help if someone else has seen this before.
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Dave(inMA)
Orange Level Joined: 12 Sep 2009 Location: Grafton, MA Points: 2395 |
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Is there an air cleaner installed and connected to the carb? Sometimes they get plugged with dirt and dust over the years which restricts air flow to the carb. Try removing the hose connecting the cleaner to the carb and see what happens.
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WC, CA, D14, WD45
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SC_MudDuck
Bronze Level Joined: 24 May 2020 Location: Mullins, SC Points: 41 |
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Thanks for your suggestion Dave.
Yes, it has an air cleaner attached. I will definitely check this out and let you know! |
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SC_MudDuck
Bronze Level Joined: 24 May 2020 Location: Mullins, SC Points: 41 |
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Yes sir, I got the same result. Ran smooth, but with high rpm and throttle didn’t matter. Guessing I need to replace the air filter. Also noticed no oil in the air cleaner cap at the bottom. Would that have anything to do with it?
I have the service manual but there is little in the way of a troubleshooting section. |
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Boss Man
Orange Level Joined: 03 Mar 2018 Location: Greenleaf, WI Points: 608 |
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The oil is the air filter. You can wash the screen out out with gas or mineral spirits but there is no filter to actually change.
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Boss Man
Orange Level Joined: 03 Mar 2018 Location: Greenleaf, WI Points: 608 |
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First thing I would do is go back through the carb. Take a thin wire and poke into all the small holes you can find and then blow out with compressed air. Been long time since I worked on my B's carb but thinking the 3 screws your are talking about are the one on the throttle shaft that sets how closed the butterfly can go. That will effect idle speed. One is a idle air screw. The more you turn it out the leaner the idle mixture is. The 3rd screw is you main mixture screw. Turning it in leans the mixture. If that screw is binding in the packing it might not be screwing in far enough for proper adjustment
Edited by Boss Man - 25 May 2020 at 11:13am |
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Bill Long
Orange Level Joined: 12 Sep 2009 Location: Bel Air, MD Points: 4556 |
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First let me congratulate you for obtaining my favorite Allis Chalmers Tractor - the B. You will find it to be a most dependable, easy to operate, and easy to work on.
On the carburetor I know they can never be cleaned enough. I remember Pop taking them apart on newspaper and cleaning several openings in the bottom with very small wire. As said above it would be wise to clean the air cleaner filter with gasoline, kerosene, or other suitable cleansers. After that put some 20 weight or similar oil in them. Sounds like you are taking good care of my favorite. Let us know how it goes. Good Luck! Bill Long
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SC_MudDuck
Bronze Level Joined: 24 May 2020 Location: Mullins, SC Points: 41 |
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Thanks everyone for your responses. I am trying to figure out how to take the air cleaner element out at the moment, but at least there is oil in there now. Great news though, I did solve part of this riddle! Looking at the rebuild kit diagram for the carb (and watching the Rachel Gingell video multiple times), it showed the "spring" that holds the needle to the float above the seat assembled. Well, the service manual shows it removed. So I tried it without the spring and wouldn't you know it, she smoothed right out. No black smoke, not surging or sputtering. After adjusting the idle speed screw and the idle air screw to where it sounded good (and wouldn't bog down in 2nd and 3rd), I cannot get the RPM to come down. The idle speed screw is about a 1/4 turn from not touching the stop, the idle air screw is at the recommended setting, and this model has a fixed main jet so it is all the way in. I am hoping to hit the same idle from the hand crank video by woodsman that I have seen others on here praise as the gold standard. I did not adjust the new float at all as the service manual says to basically shim it with gaskets or something like that. I am also getting very little throttle response until I go above 1/2 throttle (4-5 notches), this can't be normal, right?
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Dave(inMA)
Orange Level Joined: 12 Sep 2009 Location: Grafton, MA Points: 2395 |
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No - that isn't normal, SC. Both the engine speed at "idle" and the position of the idle speed screw sound wrong! And I don't get why removing that "spring" you mentioned affected anything, but that's for another day.
A bit about how a carb operates. You've got two "circuits": idle and high speed. High speed is pretty much anything above low idle. Carb will operate on one or the other circuit. At low idle, the throttle plate allows fuel to enter the throat through a small opening therein. The high speed opening is blocked by the plate. It switches from idle to high speed as the throttle plate opens, engine speed increases, and the vacuum pull through the carb increases - more fuel and more air fed to the engine. What you're describing sounds like an engine running on the high speed circuit. And that might be happening because the throttle plate isn't correctly adjusted in the throat. You can tell by looking at the plate to see if it closes properly so only one of the two fuel openings is exposed. If not, try this: Loosen the two screws that secure the plate to the throttle shaft. Make sure that the plate can move slightly across the shaft. Using the shaft, close it sharply a few times - you're trying to shift the plate slightly in the throat so it closes properly. Among other things, you're going to want to have the idle speed screw set so that the idle fuel opening is exposed above the plate.
Good luck - let us know! |
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WC, CA, D14, WD45
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SC_MudDuck
Bronze Level Joined: 24 May 2020 Location: Mullins, SC Points: 41 |
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I did notice that the plate did not completely close off to the exhaust. I will pull it again and play with the plate. |
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SC_MudDuck
Bronze Level Joined: 24 May 2020 Location: Mullins, SC Points: 41 |
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Good news friends, I come to you with hope and optimism. I may have solved my first mystery with all of your help.
So I took Dave’s recommendation and got the the throttle plate reseated correctly. Well, that made everything I did yesterday go backwards, black smoke and surging was resurrected, but I had throttle response again. So, I decided to change out the throttle lever bc the plate being reseated HAD to help! I proceeded to switch out the brand new throttle lever for the original one I replaced. Well, again no change, so I pulled the main jet plug and things got better. I then took Dave’s advice again and took off the air cleaner hose (again better), and then decided to chase it further. So I replace the hose and took off the air cleaner oil cup (again better). Replaced the cup and then chased the next joint, the air cleaner cap. When I pulled the cap off outside the hood, everything went smooth. Looking inside the cap, it is smut black. Thinking that I may replace the cap since the system below is as it should be and running smooth. What are your thoughts? If this work I will then replace the “spring” that holds the needle above the seat and see what happens. I hope this works. The idle sounded so smooth and it ran through the throttle from low to high and died as it should when pulled all the way down. Getting excited! |
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Boss Man
Orange Level Joined: 03 Mar 2018 Location: Greenleaf, WI Points: 608 |
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Should be able to soak the cap in gas, diesel or mineral spirits and clean it up. Sounds like you have a good handle on the issue.
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SC_MudDuck
Bronze Level Joined: 24 May 2020 Location: Mullins, SC Points: 41 |
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Popped it off this morning and poured some gas in this morning before taking off for work. Fingers crossed this is the issue! Thanks you Boss Man for helping me with the terminology to make my descriptions make more sense.
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Dave(inMA)
Orange Level Joined: 12 Sep 2009 Location: Grafton, MA Points: 2395 |
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Hey, MudDuck - great to hear that you're making progress. Keep at her - let us know how you're progressing.
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WC, CA, D14, WD45
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SC_MudDuck
Bronze Level Joined: 24 May 2020 Location: Mullins, SC Points: 41 |
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So Team Friends, we have success!!!
I soaked the air cleaner cap in gas this morning for 13hrs. It was SUPER nasty coming out! I decided to stop by the local big box TSC and found a breather cap for a Ford on clearance for 5.99 (plan b). So I re-assembled the air cleaner, slapped’er all the way down and it was black smoke and surging...on to plan b! Slapped’er on there and NO WAY, black smoke again! Since it was running I was going to confirm that it still drew good air with the breather off. As I started to slip it off it started to run better! So, today I learned that you shouldn’t put the breather ALL THE WAY DOWN or it won’t suck air! Successfully recreated this with the OG breather cap. Took her around the yard and she ran like a dream in all gears and throttle positions. Could have been the issue the whole time. Good lesson learned! I even took the carb back out and added the clip that holds the needle...running as intended! Speaking of lessons, I learned that I have a pinhole in the oil bath cap! It’s a good thing I have some plasti-dip to fill that puppy up, otherwise I’ll find another solution. Next issues to tackle...leaky exhaust manifold gasket, pouring hydraulic cylinder, possible wrung off bolts attaching the manifold. Separate threads of course, but really appreciate the feedback and engagement from you guys here! |
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Dave(inMA)
Orange Level Joined: 12 Sep 2009 Location: Grafton, MA Points: 2395 |
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Well done, MudDuck. Thanks for the update! The good news is that you now know a LOT about how air and gas get to the engine.
Dave |
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WC, CA, D14, WD45
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SC_MudDuck
Bronze Level Joined: 24 May 2020 Location: Mullins, SC Points: 41 |
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Absolutely. Thanks again everyone!
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SC_MudDuck
Bronze Level Joined: 24 May 2020 Location: Mullins, SC Points: 41 |
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When does one decide to replace the exhaust manifold?
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Dave(inMA)
Orange Level Joined: 12 Sep 2009 Location: Grafton, MA Points: 2395 |
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MudDuck, it depends! Please tell us what's going on with that manifold. Pictures or even better video would help a lot.
Dave
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WC, CA, D14, WD45
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SC_MudDuck
Bronze Level Joined: 24 May 2020 Location: Mullins, SC Points: 41 |
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My girl is running well for sure, but more so wondering when the right time is. I am leaking at the head manifold junction, pretty sure it is the gasket. Seems as though previous owner wrung some bolts off, and it’s pretty worn as in rusty. I’ll provide pictures tomorrow but just wondering. The exhaust is caked Internally with carbon when I look in the top and the carbon is around the rim of the exhaust insertion about an inch.
The other day she’s coughed (good thing I had a Kleenex) when she ran out of fuel and black smut poofed out. More concerned about the leaky gasket and wrung off bolts than running outta fuel. |
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SC_MudDuck
Bronze Level Joined: 24 May 2020 Location: Mullins, SC Points: 41 |
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Thought I would share a few photos.
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SC_MudDuck
Bronze Level Joined: 24 May 2020 Location: Mullins, SC Points: 41 |
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Leaky areas
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SC_MudDuck
Bronze Level Joined: 24 May 2020 Location: Mullins, SC Points: 41 |
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Loped the ole girl around the property for about a mile or so in 2nd and 3rd and she ran great!
Edited by SC_MudDuck - 06 Jun 2020 at 3:06pm |
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Boss Man
Orange Level Joined: 03 Mar 2018 Location: Greenleaf, WI Points: 608 |
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Leaking around the muffler pipe is of no concern other than water getting down through there. If its leaking between manifold and head get the right gaskets and change as soon as convenient. I've seen heads damaged from the exhaust leaking and it can be hard on the valves.
Edited by Boss Man - 06 Jun 2020 at 6:45pm |
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Dave(inMA)
Orange Level Joined: 12 Sep 2009 Location: Grafton, MA Points: 2395 |
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Agree with Boss Man. Also, the rusty complexion of your exhaust manifold is not a concern. What I'm not sure about is your concern about "wrung off bolts" - I'm not seeing that in the pictures; I do see that someone replaced one manifold stud with a bolt which likely ought to be corrected. But not a huge issue.
Glad you had a nice ride around your land!
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WC, CA, D14, WD45
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