1948 Farmall cub

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Bhalley28
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Joined: Wed Aug 10, 2016 6:57 pm
Zip Code: 48412

1948 Farmall cub

Postby Bhalley28 » Wed Aug 10, 2016 7:09 pm

I have a 1948 farmall cub that was given to me by my grandfather. It will start and idle fine. Will drive in first gear, runs ruff in 2nd, and will stall in 3rd. Also stalls when I engage the PTO. I have checked basic things(spark, flushed gas tank, new gas, compression, air cleaner). Looking for suggestions on what to try next. Thanks in advance

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Glen
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Tractors Owned: 1956 Farmall Cub with Fast Hitch, F-11 plow, Disc, Cultivator, Cub-22 mower
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Location: Wa.

Re: 1948 Farmall cub

Postby Glen » Thu Aug 11, 2016 12:52 am

Hi,
Welcome to the website. It sounds like the main jet on the carburetor could be plugged. It is shown in the pic below from TM Tractor. It is the brass colored hex bolt head on the side of the carb, near the bottom. That is the IH style carb, that is what it originally came with.
Shut off the gas, unscrew it and pull it out, use a small soft wire, run it the holes, especially the end hole. Blow it out with air, if you have that.
You could check the gas flow while it is out. Catch it in a clean can, it should have a good steady gas flow.
The jet might need a new gasket if the old one is broken. They have them at TM Tractor below. Tighten it gently, the carb is soft metal, the threads in it can strip tightening too hard.

A tune up would be good. The spark plugs might need cleaning or replacing. The spark plug wires have to be good. The points probably need filing or replacing if they haven't been looked at in years. The magneto cap or rotor might need replacing if the contacts look burned, or worn. The timing should be set with a timing light.
Some people changed them to a Battery Ignition Unit, it could be that or a magneto. :)

http://www.tmtractor.com/new/fl/4873fp.htm
Attachments
Carburetor.jpg

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Rick Spivey
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Re: 1948 Farmall cub

Postby Rick Spivey » Thu Aug 11, 2016 4:57 am

Mine did that, and it turned out to be a weak magneto coil. In addition to no power under load, it would start easy one time, hard the next. No good way to test them, but your spark has to be whitish-blue; if yellow, too weak.
Rick Spivey
'52 Cub ("Great Personality") 148xxx
'48 Cub with FH ("Gunny Cub") 38xxx
'57 Lambretta (a slow work in progress)
'74 Triumph TR6 (Mama's toy)

Eugene
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Re: 1948 Farmall cub

Postby Eugene » Thu Aug 11, 2016 5:34 am

Couple probable causes. Low compression and ignition related.

Another cause for yellow spark besides the coil is a faulty condenser.

Check and double check the location of the spark plug wires on the distributor cap. The engine will run on 2 cylinders.
I have an excuse. CRS.

Bhalley28
Posts: 3
Joined: Wed Aug 10, 2016 6:57 pm
Zip Code: 48412

Re: 1948 Farmall cub

Postby Bhalley28 » Thu Sep 08, 2016 7:39 am

Thanks again for the advice guys. I cleaned the main jet on the carburetor and replaced plugs, points, and condenser and it seams to of fixed the problem.

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Urbish
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Re: 1948 Farmall cub

Postby Urbish » Thu Sep 08, 2016 8:25 am

Welcome to the forum. You will find no shortage of good information here. There is hardly a single topic related to the maintenance and workings of a Cub that isn't covered on here. Since the tractor is new to you, I would encourage you to read and follow the steps outlined in this forum post: http://farmallcub.com/phpBB2/viewtopic.php?f=1&t=91765&hilit=cub+brought+home


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