Carb rebuild

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BucketHead
10+ Years
10+ Years
Posts: 88
Joined: Thu Aug 09, 2007 2:07 pm
Zip Code: 01050
Tractors Owned: 1963 MF 202
1953 Super C
1949 Cub
1970 LoBoy 154
1949 M
Location: Western Mass.

Carb rebuild

Postby BucketHead » Sun Sep 19, 2021 12:50 pm

I'm rebuilding the IH carb on the '64 that I brought home a couple of months ago. I got the complete rebuild kit that has the new felt seals for the throttle shaft and the choke shaft. My question is, do these felt seals get installed dry or do they get soaked in oil first?
Karl

Bob McCarty
Team Cub
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Zip Code: 80501
Tractors Owned: Cubs, MH Pony, Shaw, Allis G, 1934 Silver King, JD LA and LI, Gibson D, David Bradley Tri-Trac
Circle of Safety: Y
Location: CO, Longmont

Re: Carb rebuild

Postby Bob McCarty » Sun Sep 19, 2021 1:55 pm

Dry. If the shafts are still fairly tight, you may not need to replace the seals. If you can carefully remove and reuse the retainers, I like them better than the thinner replacements.
"We don't need to think more,
we need to think differently."
-Albert Einstein

BucketHead
10+ Years
10+ Years
Posts: 88
Joined: Thu Aug 09, 2007 2:07 pm
Zip Code: 01050
Tractors Owned: 1963 MF 202
1953 Super C
1949 Cub
1970 LoBoy 154
1949 M
Location: Western Mass.

Re: Carb rebuild

Postby BucketHead » Sun Sep 19, 2021 3:08 pm

Thank you!
Karl

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Glen
5+ Years
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Posts: 5063
Joined: Mon Mar 19, 2012 7:33 pm
Zip Code: 00000
Tractors Owned: 1956 Farmall Cub with Fast Hitch, F-11 plow, Disc, Cultivator, Cub-22 mower
Circle of Safety: Y
Location: Wa.

Re: Carb rebuild

Postby Glen » Sun Sep 19, 2021 8:00 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.
Don't use the float level specs shown for the Zenith carb, for an IH carb, they are different.
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.
The main jet is number 28 in the pic.

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.
The 2nd pic shows cleaning the main jet. :)
Attachments
Cub float.jpg
Cub float.jpg (13.96 KiB) Viewed 158 times
Cub jet.jpg


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