IH Carburetor - Idle System Disabled...

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bikerran53
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Joined: Fri Jun 04, 2021 8:44 am
Zip Code: 16354
Tractors Owned: '49 Cub - c22 sickle mower
'64 Cub - Kub Klipper 46d mower, 54a plow/snow plow
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IH Carburetor - Idle System Disabled...

Postby bikerran53 » Sun Mar 20, 2022 5:23 pm

While rebuilding an IH carburetor to address a weeping main gasket, I discovered that a previous owner came up with an unusual solution to address what I would guess was either a clogged idle jet and/or idle tube. Idle adjust screw, all the way in (so much so, it was very difficult to free up to get off), and the idle discharge holes in the main body were plugged (my issue now is how this was accomplished). I presume the idle screw on the main throttle plate was set to appropriately compensate.

As background, I never had problems starting the tractor, or it running at idle. The choke rod had been removed (which I am now suspicious as to why), and I found I only needed to briefly manually apply the choke (about 1/2 way) when it has been 45 or below. Warmer than that, it started right up without fail. I have used the Cub to plow this winter, and was always able to get it started with very little hassle.

Not the absolutely safe way to start it... in neutral, standing to the side of it so I can reach the choke lever on the carb and pull the start rod at the same time. (I recently acquired a choke rod for my rebuild...)

I did not realize this unusual solution until I had the carburetor totally apart. The chamber behind the idle discharge holes was apparently opened up by filing a wall of it away. The discharge holes appear to have been plugged with some type of sealant, as well as plugging the hole leading back to the idle adjustment screw. I am going to attempt to post pictures. The idle discharge holes and idle tube are clear now, the idle jet might remain partially blocked - i do feel some air coming out from the idle adjustment screw hole, and a gap next to the venturi when i have 80 lbs of air pressure going through the idle tube - not as much as I would expect though.

Last piece of info - more concerned with having a working tractor, and not a restoration.

My question for those of you knowing these carburetors well - what option should I pursue?

1 - rebuild the carb and disable the idle system in a similar manner?
- not sure how easy it will be to find the right idle setting for the main throttle plate
- is this an option looking for problems?
- thought it might be worthwhile to try since I have the rebuild kit

2 - replace the carburetor
a - get another used one and rebuild (use the kit I already have)
b - get a cheaper one and see how long it lasts
c - get a more faithful reproduction at a higher cost

3 - ????

ih_carb_open_idle_discharge_hole.jpg
light in idle discharge hole

ih_cub_carb_profile.jpg
profile view

Ih_cub_carb_side.jpg
angle view

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Don McCombs
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Re: IH Carburetor - Idle System Disabled...

Postby Don McCombs » Sun Mar 20, 2022 6:11 pm

If it was me, I would opt for 2a. That, of course, depends on which rebuild kit you used.
Don McCombs
MD, Deep Creek Lake

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Bill Hudson
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Re: IH Carburetor - Idle System Disabled...

Postby Bill Hudson » Sun Mar 20, 2022 9:29 pm

PM sent.

Bill
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Gary Dotson
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Re: IH Carburetor - Idle System Disabled...

Postby Gary Dotson » Mon Mar 21, 2022 7:42 am

We always say, here on the forum, that these IH carbs can, pretty much, always be saved. I think this one is the exception. I, too like option 2a, if you can find a reasonably priced one. I’ve no idea why someone would do that to one.

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Re: IH Carburetor - Idle System Disabled...

Postby SamsFarm » Mon Mar 21, 2022 10:20 am

3) jb weld and maybe some drilling! ???

Dont know if it would work, just a thought

bikerran53
Posts: 5
Joined: Fri Jun 04, 2021 8:44 am
Zip Code: 16354
Tractors Owned: '49 Cub - c22 sickle mower
'64 Cub - Kub Klipper 46d mower, 54a plow/snow plow
''72 154 Cub Loboy - Woods 59 mower

Re: IH Carburetor - Idle System Disabled...

Postby bikerran53 » Mon Mar 21, 2022 9:25 pm

Thanks for all the feedback.
You helped confirm the way I was leaning - 2a. :D

SamsFarm idea is intriguing... :idea: If PB can release the idle tube without it breaking, maybe I'll give it a try - after I have another rebuilt carb installed on my tractor.

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Don McCombs
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Posts: 16261
Joined: Mon Feb 03, 2003 6:45 am
Zip Code: 21550
Tractors Owned: "1950 Something" Farmall Cub
1957 Farmall Cub w/FH
1977 International Cub w/FH
1978 International Cub
1948 Farmall Super A
Circle of Safety: Y
Location: MD, Deep Creek Lake

Re: IH Carburetor - Idle System Disabled...

Postby Don McCombs » Mon Mar 21, 2022 9:34 pm

Which rebuild kit did you have/use?
Don McCombs
MD, Deep Creek Lake

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Proud Member of Maryland Chapter 39
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bikerran53
Posts: 5
Joined: Fri Jun 04, 2021 8:44 am
Zip Code: 16354
Tractors Owned: '49 Cub - c22 sickle mower
'64 Cub - Kub Klipper 46d mower, 54a plow/snow plow
''72 154 Cub Loboy - Woods 59 mower

Re: IH Carburetor - Idle System Disabled...

Postby bikerran53 » Mon Mar 21, 2022 9:51 pm

I actually have two. One is the IH Basic (not sure about rules mentioning suppliers - it's from a reputable one). That was going to be used on the above. The second is for a Zenith 68 series (reputable supplier). I recently successfully rebuilt a Zenith c71523r91 for my 154. A friend has a similar Zenith on her dad's '48 which I had gotten a second kit for - though it runs decent now.

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Don McCombs
Team Cub Mentor
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Posts: 16261
Joined: Mon Feb 03, 2003 6:45 am
Zip Code: 21550
Tractors Owned: "1950 Something" Farmall Cub
1957 Farmall Cub w/FH
1977 International Cub w/FH
1978 International Cub
1948 Farmall Super A
Circle of Safety: Y
Location: MD, Deep Creek Lake

Re: IH Carburetor - Idle System Disabled...

Postby Don McCombs » Tue Mar 22, 2022 6:30 am

If the IH kit includes a Viton tipped needle and seat, you may want to consider using the original steel needle and brass seat. The Viton needles have been known to stick in the closed position.
Don McCombs
MD, Deep Creek Lake

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Proud Member of Maryland Chapter 39
Circle of Safety


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