Farm Equipment - UC Running help needed

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UC Running help needed

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=13527
Printed Date: 01 Feb 2025 at 5:01pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com

Topic: UC Running help needed

Posted By: johnny
Subject: UC Running help needed
Date Posted: 07 Jun 2010 at 4:24pm

I am in need of some help. I have my uc that I bought a while back. I got it running and found it had two exhaust valve seats dropped out of the head and would not let the those 2 exhaust valves close. So I took the head off and had a very reputable rebuilder do the work. We replaced all exhaust valves, seats, and guides, we did the same on the intake side. I put he head back on new gaskets for head, intake, and exhaust. I put on new carb to intake gasket and when I fired it up it run but would accelerate then decelerate kinda like fast slow fast slow I tried to adjust the carb to no avail. I then had the carb rebuilt, the guy has rebuilt many carbs for me in the past and I have never had a problem with any carb, when I put the carb back on I had the same problem again.

I would appreciate any ideas or question you might have to help me figure this out.

thanks

johnny

Replies:

Posted By: Fred in Pa
Date Posted: 07 Jun 2010 at 6:07pm

Air tube !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Posted By: johnny
Date Posted: 07 Jun 2010 at 7:12pm

Just pulled the breather assm apart no blockages and started tractor with no breather connected to carb same thing.

Thanks
Johnny

Posted By: CTuckerNWIL
Date Posted: 07 Jun 2010 at 7:39pm

Fred is talking about the air tube in the manifold I believe. It can rust through or burn out causing a loss in vacuum pressure at the carb and I believe sucking exhaust in if I understand it right. My CA wanted to do that too but it didn't have the proper anti surge spring on the throttle linkage.

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http://www.ae-ta.com" rel="nofollow - http://www.ae-ta.com
Lena 1935 WC12xxx, Willie 1951 CA6xx Dad bought new, 1954WD45 PS, 1960 D17 NF

Posted By: Ted in NE-OH
Date Posted: 07 Jun 2010 at 7:56pm

Sounds like a carb linkage or govenor problem.

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CA, WD, C, 3 Bs, 2 Gs, WC, I-400, 914

Posted By: CTuckerNWIL
Date Posted: 07 Jun 2010 at 8:07pm

When the engine is surging, grab hold of the throttle shaft in the carb and hold it in one place. If the engine runs smooth, the problem is most likely caused by slop in the linkage or governor. If when holding the throttle shaft in one position the surging continues you may have an internal leak in the manifold. I really don't know how the engine would act with the burned out air tube (I'm sure Fred does).

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http://www.ae-ta.com" rel="nofollow - http://www.ae-ta.com
Lena 1935 WC12xxx, Willie 1951 CA6xx Dad bought new, 1954WD45 PS, 1960 D17 NF

Posted By: johnny
Date Posted: 07 Jun 2010 at 11:51pm

Thanks for the ideas, Sorry I mis-read you Fred. On the manifold where the elbow comes out and goes up for the exhaust pipe I see two bolts on a larger cover plate. If I take off that cover will I see the problem if it is the air tube inside?

I will try holding the carb linkage steady and see what happens.

Thanks

johnny

Posted By: skipwelte
Date Posted: 08 Jun 2010 at 11:35am

On the older ones you have to separate the top and bottom halves of the manifold to get to the air tube, dont know about the later ones. HTH