Cub Carb

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Captain Ron
Posts: 20
Joined: Tue Oct 04, 2016 7:40 pm
Zip Code: 40299

Cub Carb

Postby Captain Ron » Thu Nov 03, 2016 8:55 pm

I have a IH 3/4" carb and a rebuild kit for my 1948 Cub, but I think I need a manual to rebuild it. It looks like I may have a jet thats broken. Does anyone know if there is a IH Cub Carb rebuild/Parts Manual available some where?

Thanks.... Ron

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

Re: Cub Carb

Postby Bob McCarty » Thu Nov 03, 2016 9:38 pm

Here's a link to a how to by Don McCombs: viewtopic.php?f=139&t=83618
The next place to look is the GSS-1411 Blue Ribbon Service Manual that's available in the PDF Manuals above.
The first important thing is to make sure you pull the two halves straight apart or you risk breaking the idle tube. I've seen a few main jets that had the threads broken off the end. There are few things that can't be repaired on an IH carb. Post pics if you can.

Bob
"We don't need to think more,
we need to think differently."
-Albert Einstein

staninlowerAL
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Tractors Owned: Cubs: (3)'49's, (1)'52, (1)'57 IH Cub LoBoy w/FH, (1)'72 154 Number Series Loboy, '76 Longstripe w/FH, Mowers: C-22, Bush Hog 412, Pennington 59, Woods RM42CF, Woods 42, assorted FCub plows, planters, discs, etc. OTHERS: '49 AC B & Ind. Sickle mower, '61 AC D12 Ser 2, '52 8N, '56 Ferguson 35 Deluxe, '53 MM BG (offset), (2) '49 Avery V's, '51 JD M (regular), '56 JD 420C, with Blade and fire plow, '85 JD 850 (Yanmar) w/72" belly mower, '76 Yanmar 1500, Sears Surburban's, MTD's, Jeeps & other misc. "treasures"
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Re: Cub Carb

Postby staninlowerAL » Thu Nov 03, 2016 9:42 pm

Sounds like you might have a broken idle jet tube between the top and bottom halves of the carb. Not uncommon but can be a "bear" to remove. The bottom part just sticks down in the hole in the bowl, (lower half of the carb). Start by soaking the upper end in the carb top with a penetrating lube like KROL/PB Blaster, etc. Don't expect magic and have plenty of patience. After toroughly soaking for a while, start with a very small left hand drill bit, I believe its a #4, and HAND DRILL (NO POWER TOOL HERE). If you get lucky, the drill bit will catch and back the broken piece out. It's not very long and don't go deep enough to damage the threads in the top half of the carb. Once you get the broken piece out, the threads can be cleaned up with a tap if needed. I believe it is a #48. Someone will probably post the correct sizes or you can search the forum for other threads on this topic, it's been covered several times before. Best price on a replacement is probably McDonald Carb. Here's a post from the BOK/Fuel by Don McCombs, it's about as thorough as you will find from one of the forum carb experts. viewtopic.php?f=139&t=83618
Once again, Bob (another forum carb expert) beats me to the draw. :lol: :surrender: :hattip:

Bob McCarty
Team Cub
Team Cub
Posts: 8938
Joined: Tue May 25, 2004 8:02 pm
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: Cub Carb

Postby Bob McCarty » Thu Nov 03, 2016 9:48 pm

If it is the idle tube (http://www.tmtractor.com/new/fl/384fp.htm), the tap size is 4-48. The drill size for that tap is a #42 or closest fractional is 3/32. Start with a slightly smaller left hand drill bit as Stan suggested.

Bob
"We don't need to think more,
we need to think differently."
-Albert Einstein

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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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Re: Cub Carb

Postby Glen » Fri Nov 04, 2016 12:52 am

Hi,
Here are 2 pages from the Cub parts book showing the IH carburetor. The pic is helpful to see how it should fit together.
I would soak especially the top and bottom castings in solvent, or carb cleaner, and then blow all the passages out with compressed air. Dirt settles in the bottom half, but could be anywhere inside the carb. Wear your safety glasses when using the air.
When you get it put together, the idle screw on top of it should be open 1 - 1 1/2 turns, the owner's manual tells how to adjust it, you run the engine at idle speed, supposed to be 500 RPM, and listen to the engine, while adjusting the screw. Set it so it idles as good as it will.
It says adjust it when the engine has warmed up. Good luck. :)

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

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

Captain Ron
Posts: 20
Joined: Tue Oct 04, 2016 7:40 pm
Zip Code: 40299

Re: Cub Carb

Postby Captain Ron » Fri Nov 04, 2016 1:35 pm

Yup, I broke the idle tube- it was very difficult to separate the two halves, even though I was very careful. Ugh...
I'll get the right size drill & tap and careful remove it after a long soaking in cleaner.

Thank you, gentleman! You guys are awesome to have as friends.

Ron

Bob McCarty
Team Cub
Team Cub
Posts: 8938
Joined: Tue May 25, 2004 8:02 pm
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: Cub Carb

Postby Bob McCarty » Fri Nov 04, 2016 1:38 pm

Ron, Your Cub may run okay with the broken idle tube. The calibrated orifice is in the short threaded end. Hopefully the long piece will slip out after soaking, that one can be a bear to drill out.

Bob
"We don't need to think more,
we need to think differently."
-Albert Einstein

Captain Ron
Posts: 20
Joined: Tue Oct 04, 2016 7:40 pm
Zip Code: 40299

Re: Cub Carb

Postby Captain Ron » Mon Nov 07, 2016 11:45 am

Okay, thank you, Bob. :)


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