My cub isn’t running

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DKoons
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Zip Code: 44833
Tractors Owned: 1949 Cub

My cub isn’t running

Postby DKoons » Sun Dec 06, 2020 4:38 pm

Hello everyone my name is Devin and I’ve had my 1949 cub for about 2 years now. When I first got her I rebuilt the carb and she’s been running a bit rich since I did that. Now this year she isn’t running at all and has fuel fouled 2 sets of plugs. Not sure what to do and what kind of plugs I should put back in her. She currently has Autolite 3116 in now. Any help would be appreciated, Thanks

I have also replaced her wires and she seems to have spark. I believe she is getting too much fuel and I think I have set the float height and drop correctly :help:

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Re: My cub isn’t running

Postby Eugene » Sun Dec 06, 2020 5:24 pm

Welcome.

You said fuel fouled spark plugs. Could it be oil fouled spark plugs?

Debris between the needle valve and seat will cause running rich.

Suggest a complete engine tune up. Starting with compression tests. Compression tests will provide a very good indication of the engine's health.

You could try hotter spark plugs hopefully to burn off some of the fouling. But start with the tune up.
I have an excuse. CRS.

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Bill V in Md
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Re: My cub isn’t running

Postby Bill V in Md » Sun Dec 06, 2020 5:33 pm

I would revisit the carburetor setup, especially the float setting. Also check your ignition system in terms of points and timing. You need good, clean points with the proper gap. I would also check and reset the timing. The Autolite 3116 is a good non-resistor plug that is compatible with a magneto, which I assume you have. So I doubt that is your problem. Could also check the oil bath air intake cleaner, because you need good air flow for proper combustion.
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MiCarl
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Re: My cub isn’t running

Postby MiCarl » Sun Dec 06, 2020 9:31 pm

I will add that you shouldn't just go by the float height. Do a fuel level check as described in the service manual. I found that my fuel level was 3/16" too high when I set the float height to spec.

It's entirely possible that something in my carburetor isn't original or to original spec. Can you be certain all yours is after 71 years?
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DKoons
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Joined: Thu Dec 06, 2018 10:38 am
Zip Code: 44833
Tractors Owned: 1949 Cub

Re: My cub isn’t running

Postby DKoons » Mon Dec 07, 2020 3:40 pm

Thank you for the advice. I hope to get back into the shop this week to work on her. I will post an update hopefully by next weekend

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Stanton
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Re: My cub isn’t running

Postby Stanton » Mon Dec 07, 2020 7:15 pm

DKoons wrote:Thank you for the advice. I hope to get back into the shop this week to work on her. I will post an update hopefully by next weekend


I was having the same problem a while back; fouling plugs, not running right. I found out the fuel jet orifice was too big. I replaced it with a 0.030 size and it solved the rich running issue.

Check out this thread (remember, the smaller the jet opening the leaner the fuel mixture):http://farmallcub.com/phpBB2/viewtopic.php?t=107871
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Re: My cub isn’t running

Postby Stanton » Mon Dec 07, 2020 7:24 pm

BTW: Welcome to the Forum!

Take some time and read through a few threads to acquaint yourself with the Forum:

Now that you have 2 posts, you'll have access to all the PDF Manuals on this site. There’s a few ways to do that:
  • From a desktop or laptop, go to "Quick Links" in the upper left corner of your screen. Hit that and a pull-down appears where you'll find "PDF Manuals".
  • You can also go to “Cub Info” in the upper toolbar, then hit “Rudi’s Manuals”. From there, you can access a variety of information.
  • If you're using a phone, go to the "Links Directory" (second category down the main page). Once in "Links Directory" , scroll down to the second section "Tractor Parts & Manuals" and you'll find them there.

We’d encourage you to take the Safety Test located in the Safety Forum: http://farmallcub.com/phpBB2/viewtopic.php?f=33&t=68084

Take some pictures of your tractors and post them, we’d like to see them.

Remember:
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Glad you joined us.

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Glen
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Re: My cub isn’t running

Postby Glen » Mon Dec 07, 2020 10:27 pm

Hi,
Here is some info for cleaning and repairing the IH carburetor, if you need it.

Before taking the carb apart, clean the outside of it, to keep dirt out of the carb.
When taking it apart, pull the 2 halves of the carb straight apart several inches, there is a small idle tube that screws into the top half of the carb, it can break if you twist it, or don't pull the 2 halves straight apart.

Use carb cleaner, or solvent to clean inside the carb.
All the passages need to be open and clean.
Blow them out with compressed air, and be sure they are open. Use your safety goggles when using the air.
Remove the main jet, the 6 sided brass colored part low on the side of the carb, and run a small wire in the hole in the end of it, to be sure it is open, and then wash the jet.
Tighten it gently, it can break. It should have a fiber washer under the head, to seal it, sometimes if the washer is old, it won't seal if you reuse it.

The needle and seat could have dirt in it, making it not seal. Remove the float and the needle and check for dirt, clean the needle and seat.
Check the float, it should look in good condition, not collapsed or corroded.
Shake it gently while it is off, it has to be dry inside, no gas inside it.
If it is good, it can be used again.
Assemble the needle and float again.

It is important that the float level and float drop be set exactly.
People on here have said that their carb wouldn't work right until they set the float level exactly.

Below is a page from the Cub service manual showing setting the float height.
The IH carburetor is in the upper pics on the page, the Zenith carb in the lower pics.
To set the float level, turn the top half of the carb upside down, like the pic of the Zenith carb, in the lower right of the page.
The gasket between the halves has to be off, when measuring the float level of the IH carb.

http://www.farmallcub.info/manuals/gss- ... 002-09.jpg

Bob McCarty converted the measurements to use a dial caliper, it is easier.
The float level is 1.4"
The float drop is 1.6"

The tab on the float arm has to face up.
Sometimes the float is upside down.
Put it in the right way, if it is upside down.
Bend the float arm between the float and where the needle touches it, to change the float height.

Turn the top half right side up to set the float drop.
Bend the tab in or out to change the float drop.

The needle and seat could be wornout from years of use, and don't seal, then the carb can drip on the ground when the Cub is sitting.
I have seen them that were wornout, they dripped, and then it quit dripping after putting in new ones.
The IH carb has a small screen where the gas line attaches to the carb, be sure it is clean.
Tighten everything on the carb gently, the IH carb is soft metal, and threads can strip.
The carb top can warp if the screws are tightened too much.
You could check the gasket surface of the top when it is off using a straight edge.
TM Tractor, at the bottom of the page, has new carb parts.

Below are pages from the Cub parts manual showing the IH carb.

http://www.farmallcub.info/manuals/cub_ ... 012-12.jpg

http://www.farmallcub.info/manuals/cub_ ... 012-13.jpg

Cubs have a manual choke, you have to use the right amount of choke when the engine is cold, until it warms up, so it runs good.

Below is a pic of an IH carb float from TM Tractor, showing the tab for the float drop. :)
Attachments
Cub float.jpg
Cub float.jpg (13.96 KiB) Viewed 287 times

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Jim in SC
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Tractors Owned: 1951 Farmall H - "Ray R." (SN FBH 366519)
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Re: My cub isn’t running

Postby Jim in SC » Wed Dec 09, 2020 7:16 am

EXCELLENT "How to", Glen. I'm bookmarking those instructions. Thanks!
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DKoons
Posts: 3
Joined: Thu Dec 06, 2018 10:38 am
Zip Code: 44833
Tractors Owned: 1949 Cub

Re: My cub isn’t running

Postby DKoons » Wed Dec 23, 2020 1:55 pm

Update

Thanks for all the advice guys. I finally got back into the shop and worked on the old girl for a bit and turns out it was the fuel level. I also replaced the plugs and cleaned the points and made sure the timing was set. Then she started right up like nothing was ever wrong :{_}:
:tractor: Got her plowed hooked up and now waiting on the snow. Thanks again for all the help

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Don McCombs
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Re: My cub isn’t running

Postby Don McCombs » Wed Dec 23, 2020 4:30 pm

Just curious. What do you mean by fuel level? Float set improperly or insufficient fuel in the tank?
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