WD carb 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=125701
Printed Date: 07 Aug 2025 at 6:30am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: WD carb help needed
Posted By: cpg
Subject: WD carb help needed
Date Posted: 10 Jul 2016 at 8:34pm
I picked up a WD not that long ago and I am having some issues and I am probably missing something simple so I figured I would go here with all the expertise and fresh minds. The issue I am having is that the tractor will barely run with the choke off; runs okay for a few seconds then dies down and the governor opens right up for it to recover. With about half choke it will run okay with just a little miss. I have good spark, have cleaned the carb (all passages with wire, carb cleaner, and air) and set the screws and checked float height to original specs, blew out the line and sediment bowl and made sure I have good gas flow, and used starting fluid while running to check for vacuum leaks and haven't found any. It seems to be a lean condition as partial choke allows it to run but no matter how much I adjust the mixture screws it makes no difference as to how it runs. The only possibilities I can think of right now are that the power screw has some corrosion to the point of having some pitting. I have cleaned it up but still has some pitting. Also the float as indentations on the outside faces that I'm not sure if they are meant to be there or if it is dented. The float doesn't leak and it seems like if that was the issue it would be flooding not too lean. It has the Marvel Schebler TSX. Thanks for any thoughts. |
Replies:
Posted By: allischalmerguy
Date Posted: 10 Jul 2016 at 8:57pm
|
Did you try running it with out the oil bath air cleaner tube attached to it? ------------- It is great being a disciple of Jesus! 1950 WD, 1957 D17...retired in Iowa, |
Posted By: LeonR2013
Date Posted: 10 Jul 2016 at 9:28pm
| I would look at the venturi and see if it's fitting tight, then go from there. Sometimes the lips crack or even break off. If cracked just solder them up on the back side. I've seen the lips get bent and this causes an internal leak. |
Posted By: Gerald J.
Date Posted: 10 Jul 2016 at 10:24pm
|
Its running right for the original screw settings. On such vintage carburetors, those settings are just good enough it will run to allow you to tune it. With it need choking, you need to richen both the idle and the run jets, then with the choke off and the governor defeated by holding the throttle closed, adjust the idle screw for the fastest speed, then with it running fast, preferably without the governor linked, adjust the main jet for the fastest speed. Alternatively adjust slow and fast letting the governor close the throttle and adjust for minimum throttle. Repeat high and low speed adjustments until they stop changing because they do interact. Gerald J. |
Posted By: cpg
Date Posted: 10 Jul 2016 at 10:26pm
| I did run it with the air cleaner hose off and same deal. The venturi is in good shape and does fit the carb but always comes off with the gasket, it doesn't fit really snug into the carb body. Should they press in tight? |
Posted By: WF owner
Date Posted: 11 Jul 2016 at 5:39am
|
Check the simple things first. Do you have good fuel flow to the carb?
Has someone installed a fuel filter that is limiting fuel flow to the carb? Have you tried loosening the fuel cap (on the tank) to make sure enough air is getting in for full fuel flow?
Do you have a good seal on the manifold where it attaches to the block? Any cracks in the (intake) manifold? When you rule these things, you can narrow it down to a carb issue.
|
Posted By: cpg
Date Posted: 11 Jul 2016 at 5:47am
|
I have blown out the line and sediment bowl and I have good fuel flow through the hose at the carb. It did have a filter but I also tried it with a regular piece of hose and it didn't make any difference. While it was running I sprayed the seals where the manifold meets the head with starting fluid and it made no difference to the way it ran so I don't think I have a vacuum leak there either. I have tried adjusting the screws beyond the original starting specs as I usually have to on all my old tractors to tune them in but no matter how much adjustment I use it doesn't make any difference. I can make three or four full turns on the power screw and it has no noticeable effect. |
Posted By: DougS
Date Posted: 11 Jul 2016 at 6:02am
| A good float does not mean the needle valve isn't stuck or clogged. As others have said, open the plug at the bottom of the carb. |
Posted By: corbinstein
Date Posted: 11 Jul 2016 at 6:26am
| Have you tried running with the gas cap loose as per someone's suggestion? |
Posted By: cpg
Date Posted: 11 Jul 2016 at 11:25am
| I have even tried running with the gas cap off to prevent vacuum locking and it didn't help either. As usual when I clean carbs I blew air through the needle valve to make sure it was working but it is a newer neoprene tip so I know they can stick pretty easy. I think I will screw the needle valve seat right out next to be 100% sure it's clean up inside there. |
Posted By: Stan IL&TN
Date Posted: 11 Jul 2016 at 12:08pm
|
You can test the float by holding in down inside a cup of warm water. The warm water will warm the air inside the float and pressurize it. If there is a leak you will see the bubbles coming out of it. ------------- 1957 WD45 dad's first AC 1968 one-seventy 1956 F40 Ferguson |
Posted By: Gerald J.
Date Posted: 11 Jul 2016 at 2:15pm
|
Sometimes there is a filter screen on the inside if the inlet elbow that gets clogged. Gerald J. |
Posted By: DougS
Date Posted: 11 Jul 2016 at 3:31pm
|
If the float were leaking your tractor would be flooding. It seems you have the opposite problem. |
Posted By: WF owner
Date Posted: 11 Jul 2016 at 5:09pm
| Is the throttle shaft in the carb tight? They can suck some air around that shaft. |
Posted By: LeonR2013
Date Posted: 11 Jul 2016 at 9:59pm
| The venturi coming out with the gasket is OK. It seals on the ends. So if it happens to be short, then you can loose some of the suction where it draws gas into the engine. It doesn't sound like that is your real problem but is always a possibility. |
Posted By: cpg
Date Posted: 12 Jul 2016 at 8:23am
| The throttle shaft is one I haven't thought of. I will check that out today when I clean in behind the needle valve seat. |
Posted By: cpg
Date Posted: 12 Jul 2016 at 7:18pm
|
Well I pulled the carb down to pretty much the cast iron case and re-cleaned everything and it still runs the same. I did check and the throttle shaft has noticeable play in both directions, side to side and in its bore. I think my next step is get a total rebuild kit for it with new float and throttle shaft and totally go through it. |
Posted By: Steve in NJ
Date Posted: 14 Jul 2016 at 6:36pm
|
In most cases, a new throttle shaft will not fix a loose bore. The bore needs to be sleeved or bushed in order for the shaft to fit tighter. The bore is what wears, not so much the shaft. When I rebuild our customer's Carburetors, if they have a loose throttle shaft in the bore, I sleeve or bush the bores. In most cases I reuse the throttle shaft over unless it has wear or damage where the linkage rod goes into the lever. Also, just soaking a Carburetor and installing a kit doesn't always do the deed. In most cases, the Carb needs to go through a number of cleanings, including glassbeading to get all the gunk and crap out that built up over the years. Bore brushes should be used throughout the Carb to make sure idle and enrichment passages are clear as well as the inlet bore which should be free of rust and debris. Sounds like you have rust or debris lodged in the idle circuit....HTH Steve@B&B ------------- 39'RC, 43'WC, 48'B, 49'G, 50'WF, 65 Big 10, 67'B-110, 75'716H, 2-620's, & a Motorhead wife |
Posted By: CTuckerNWIL
Date Posted: 14 Jul 2016 at 6:40pm
This piece needs to be removed and cleaned. ------------- 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: cpg
Date Posted: 14 Jul 2016 at 8:04pm
| Thanks for the tips, I will make sure I check to bore and put in a bushing. I had all the parts out that would come out like the piece pictured above and cleaned it out but like you say there is probably crud down in the carb passages. My plan is to pull it apart and get a can of the chem-dip for soaking carbs and strip it totally down to the cast iron and let it soak for a while then do the total rebuild kit with new seat, float, and throttle shaft. |
Posted By: Gerald J.
Date Posted: 14 Jul 2016 at 9:13pm
|
Soaking isn't always enough. Sometimes the passages need a good brushing with a wire brush or high velocity sand blaster to move the junk softened by the soaking. Rust is harder to move. Gerald J. |