Farmall Cub Forum -- Questions and answers to all of your Cub related issues.
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Hello Everyone thanks for reading my post. I just bought a 1950 farmall Cub I have rebuilt the carburetor put a new screen and gasket for the gas bowl installed new plugs and it has pretty new spark plug wires on it and I also just installed a new rebuilt magneto. The tractor is 6 volt the problem I am having is the only way I can get the tractor started is by pull starting it and it will only run for a few minutes. I have the throttle wide open and it sounds like the tractor is at part throttle. I am confident the tractor is in time and wired up properly. Does anyone have any suggestions? I am thinking it has something to do with the Governor I have never messed with one of these tractors before it is my first and I hope to get this thing running so I can add to my collection. Any help will be appreciated.
Welcome to the forum James.
Have you checked compression on the engine? If it only runs a few minutes you may have a ignition coil breaking down,check to see if it is getting hot after tractor shuts down As far as your throttle problem It may very well be a governor problem.
You need to get the compression reading to start.
"Work smarter; Not harder"
Welcome. There are many smart people here that will get your machine up and running.
Make sure that you attached the choke/governor linkages correctly to the carburetor. After replacing the carburetor you may need to readjust the linkage to the governor. It is also possible that there may be some junk in the main carburetor jet after the cleaning. Remove the jet from the carburetor and blow it out with carburetor cleaner.
A simple check is any fuel line shut offs, like the valve at the strainer bowl. Make sure that they are fully open.
Last edited by TJG on Mon May 27, 2013 9:31 pm, edited 2 times in total.
Compression readings should be over 90(dry), but I have heard them run with lower. Make sure that the main jet is clear by removing the jet from the side of the carb and running a soft wire through the hole at the end. Also verify that you have good constant flow of fuel by removing the plug at the bottom of the carb and opening the fuel shutoff... You should have good flow all the way through.
I agree that your firing order seems right. Sounds like fuel flow to me!
Mike (Happy as a Lark in Allison Park, PA)
Check out my Restoration Thread (1955 Cub, Lewis)
Thanks TJG and Hengy I will try that tomorrow if I get time after work. I have been reading some articles here that has helped me tremendously especially on wiring and timing the magneto. I didn't know where to go from here so I figured I would join I figured you guy's would steer me in the right direction.
Looks like Mike has got you covered on the compression reading. The important part of compression readings is that they should be within 15% of each other. Do a wet and dry test as that will tell a lot more on mechanical condition.
I agree with Mike and Todd that you may have a fuel flow issue, there may be some trash in the tank causing fuel flow problems. I had this problem with with my 48 earlier this year and went ahead and pulled the tank and cleaned it.
"Work smarter; Not harder"
Welcome to the forum, and yeah, check out the fuel and governor linkage as Hengy and Marion stated. See where that gets you. Read and study the manuals and past post on the forum.
Guiena, 1951 Farmall Cub; Jumping Willy, 1949 Farmall Cub.
Good morning James,
Be very careful with pull-starting your Cub !
Many a front engine mount "ears" have been cracked/broken through pull-starting ! You'll be better off "push-starting" or even still better, getting it running by troubleshooting and self-starting in the shop !
G'day to you and congrats on acquiring your very 1st new to you Cub Before I get into your problems might I suggest that when you have a few minutes to follow the links below as there are many resources available to our members.
I have a Cub that has a similar problem as you describe. I have retimed it, it is now perfectly timed, magneto provides a bright blue spark, firing order is exactly as it should be, and for the most part the fuel delivery system while not perfect does provide the fuel as required. Because I am using a pony tank on that Cub at the moment I really believe that the fuel issues are the reason behind the requirement to pull start this Cub.
I am not sure the Governor has anything to do with it unless the governor linkages are frozen in place. If that is the case then disconnect and proceed as described above. The other problems seem like fuel supply issues to me. I would recommend that you go over your fuel circuit - How To Upgrade A Cub Fuel System - might be useful although it goes into far greater detail than may be required. You have to ensure that your fuel circuit is clean from tank to needle and cage.
The other thing that needs to be done is to ensure that the valve lash is correct and no valves are sticking. How To Adjust Valves - Method #1 and How To Adjust Valves - Method #2 are useful articles to peruse. Recheck the firing order - How To Understand Firing Order and ensure that the spark plug wires are correct. Also make sure that the spark plug wires are copper core and not composite carbon core. Carbon Core will not function with a magneto.
Question. Does the magneto click when you hand crank the engine?
Remove the hose from air cleaner to carburetor. Pull the choke lever on the dash and check to see if it's operating the choke valve in carburetor throat. -- It's easy to get the choke and throttle controls mixed up.
Diagnostic sequence. Compression, engine condition. Ignition system. Carburetion, fuel system.
I have an excuse. CRS.
Thanks Guys I have a few things to check out hopefully I can get to it Saturday I have to go out of town with work for a few days. It seems like I hardly have time for anything anymore with work and trying to redo a house. I appreciate all the reply's I will let you all know what I have found out.
Hi Fellas I think we have found out what is going on with my Cub. My dad charged the battery up and put it on my tractor while I was out of town he said it turned over twice and started ran for maybe 5 minutes and then quit gas was dripping out of the carburetor. We started it tonight when I got back and it is flooding out we are pretty sure the float is out of adjustment. Does anyone have a fast and easy way to adjust the float on the carb. It is the International carburetor with the big round float. Thanks again for all the help fellas.
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