D12 runnung rough
Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=206362
Printed Date: 29 Apr 2025 at 8:44pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: D12 runnung rough
Posted By: 54f250
Subject: D12 runnung rough
Date Posted: 19 Apr 2025 at 7:23pm
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I have a 1960 (2464) D12 I'm trying to get running after many years of barn life. It has several issues but thanks to some help from this forum it at least runs -- a little. I have replaced the carb, plugs, plug wires, and coil. It starts with full choke and runs with the choke. When I close the choke completely it runs fairly smoothly but at full throttle RPM with almost no throttle response. I cannot get it to idle or even to slow. I have tried adjusting the carb with almost no effect. I suppose I may have a bad carb (China). I have not done anything to the governor, but I keep thinking it could be a source of this issue. I would like to get it running smoothly before I move on to several other issues. Any ideas?
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Replies:
Posted By: steve(ill)
Date Posted: 19 Apr 2025 at 9:13pm
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It starts with full choke and runs with the choke. When I close the choke completely it runs fairly smoothly but at full throttle RPM with almost no throttle response Should not need full choke to start... but if it does, you should be able to get choke 90% off within a few seconds... When you say CLOSE the CHOKE, is that 100% NO CHOKE.. Butterfly OPEN ?.... It would be hard to run WIDE OPEN unless your throttle rod / lever on the carb is fully stroked.. I would look at that to see the rod is not dragging on the engine block / etc... The LEVER on the carb should be down against the STOP.. and there is a STOP SCREW to adjust the low idle positon.. See that the lever is against the STOP and that the screw is backed out to get to LOW IDLE.... IF all that works, then we can get to the governor.. ------------- Like them all, but love the "B"s. |
Posted By: steve(ill)
Date Posted: 19 Apr 2025 at 9:18pm
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BAck out the IDLE SCREW and make sure the THROTTLE ARM is down against the STOP to get to IDLE..... not your carb, but something like this.... if you have a mixture screw like the one at the top right of this picture, screw it in to the BOTTOM and back out 1.5 turns... i have a China Carb on one of my B tractors.. Starts and runs fine... but i had to remove the main jet and make it .002 inch bigger to keep it from hunting at 2/3 throttle. needed about 10% more gas..
 ------------- Like them all, but love the "B"s. |
Posted By: 54f250
Date Posted: 20 Apr 2025 at 4:28am
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Thanks for the quick response. When I say the throttle is closed I mean the butterfly is closed. I have tried adjusting the throttle set screw bit it does not seem to help. I also don't get much response from the idle or load adjust. |
Posted By: WF owner
Date Posted: 20 Apr 2025 at 6:14am
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The first place I look on these old tractors is fuel flow. I drain the gas tank and remove the sediment bowl. Many (probably actually most) of the time, I find stuff plugging up the inlet to the sediment bowl. Remove the gas shutoff and thoroughly clean the inlet, outlet and screen in the sediment bowl. I can't explain why, but one of my tractors won't run right unless it has at least 5 gallons of gas in the tank. Any less, it spits and sputters. Lastly, check and make sure you don't have Champion spark plugs in it.
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Posted By: steve(ill)
Date Posted: 20 Apr 2025 at 8:24am
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there is NO WAY for the engine to go to high RPM without the THROTTLE PLATE OPENING... If you have the throttle arm on the carb down against the STOP SCREW and the SCREW is backed out far enough, the engine has to be a LOW RPM, unless the THROTTLE PLATE inside the carb has come off..
you may have the WRONG CARB... some are setup so you PUSH on the rod and the throttle plate opens, some are setup so you PULL the rod and the throttle plate opens... again, the plate has to be OPEN to get the motor to high RPM.. ------------- Like them all, but love the "B"s. |
Posted By: HudCo
Date Posted: 20 Apr 2025 at 9:56am
| been siting for a few years ? if it does run decent ant the carb is clean and its getting fuel all four spark plugs firing ? if so better check to see iff all the valves are opening and closeing one stuck valve will make it run that way |