IH Carburetor - Idle System Disabled...

[bikerran53]

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 - ????

light in idle discharge hole

profile view

angle view

[Don McCombs]

If it was me, I would opt for 2a. That, of course, depends on which rebuild kit you used.

[Bill Hudson]

PM sent.

Bill

[Gary Dotson]

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.

[SamsFarm]

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

Dont know if it would work, just a thought

[bikerran53]

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

SamsFarm idea is intriguing... 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.

[Don McCombs]

Which rebuild kit did you have/use?

[bikerran53]

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.

[Don McCombs]

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.