Carburator dust seal problem :(

Mon Sep 24, 2007 8:18 am

Hey All,
I'm in the process of rebuilding an IH standard carb with an IH rebuild kit #354 454 R92 that Lynn sent to me last week. Per instructions carb dissasembled, cleaned, dewarped :wink: , and started assembly. Came time to install choke shaft dust seals and seems like they are to large for my carb :cry: . The new seal caps are the same as the single throttle shaft seal cap which did fit (supposed to be correct?). The new measure 7/16" and the old choke shaft cap 3/8", and actually fits inside of the new cup. Carb # as best I can see with my loop is #251234 R? and looks like another stamp to the right of the R# but defaced from PO tapping on cover at some time. I'll try to post a few pics on this post if I can figger it out. (no excuse for not knowing by now :? ) Has anyone else had this problem before?, wrong carb kit?,oddball lower half? I guess I'll have to wait to talk to TM until 10/02 but hopefully can get some input from the board first....if everyone is not at JPs' :lol:

Mon Sep 24, 2007 11:04 am

That is strange. My old caps measure .453 after I pried them out. I just rebuilt a 74 carb and earlier this year I rebuilt the carb from my 52 and both are identical. The carb experts will chime in soon I am sure and this will run the thread up to the top for now.

You can email me a pic and I'll post it for you.

Good luck.

Mon Sep 24, 2007 11:58 am

Chris, I'm not sure what's going on with your carb. I just checked 3 IH carbs and both sides of the choke shaft calls for the 7/16(.437) number 45148D felt seal retainer. The top throttle shaft calls for the same part number 45148D. The capped off side of the throttle shaft on mine measures at 5/16(.312) which doesn't need to be removed.

Some pics might show something if you get the chance later.

I just rebuilt videodocs carb at SteveB's Saturday and the retainers all fit perfect from IH :?


Tue Sep 25, 2007 7:32 am

OK...Think I got the pic thing down. Once again the problem is new IH replacement choke shaft dust seals are to large to fit into my casting. I also didn't mention that the throttle shaft is binding with the new replacement dust seal that DID fit from my IH kit. I seated it all the way and possibly a bit of crush factor going on? Give me your thoughts! :?

Tue Sep 25, 2007 7:52 am

So the throttle shaft metal seal housing was smaller than these 2?

My dust seals bind a bit upon assembly. Did you put some lubricant in the felt? Is it binding metal-to-metal or felt-to-shaft? If it is felt-to-shaft that will not last long before the felt compresses. I soak these with WD 40 for assembly and once it is assembled I put a 1 drop of light oil, like a 3-in-1 oil, on the felt.

Too bad I just installed my kit late last week. Other wise we could compare opening size on the carb and OD on the uninstalled cups. That would at least narrow down where the deviation is coming from. Do you have a vernier? I measured the OD of the cups I removed at about .453 . They get a little distorted but the measurements were fairly consistent all the way around from .448 to .458 max. which is larger than the .437 (7/16") that was mentioned by 1/64.

Tue Sep 25, 2007 8:04 am

Chris, the seal retainers for the throttle shaft worked, and the "Choke Shaft" seals are too small? You may have an odd ball carb? I checked thru some of the manuals we have been converting to PDF, and I find TWO seperate part numbers for the choke shaft seal and retainers for the IH carb.

You may very well have the early carb, IH part number 251-234-R91?

If so, I see two possible part numbers for the choke shaft dust seal retainers (as well as 2 different felt seals as well), the 1st number is 251-306-R1 and that states it is for the IH carb 251-234-R91 The 2nd part number is 45-148-D and it states it is for IH carb 251-234-R92.

I don't see 2 different possible part numbers for the throttle shaft, just for the choke.

Is your Cub by chance an early '47 model?

Tue Sep 25, 2007 8:11 am

This is interesting. i think I found what's what. Seems IH started with carb number 251234R91, then quickly updated to 251234R92. It appears you have the 92 top with the old 91 bottom. The old 91 bottom calls for retainers #251306R1, but all the new kits only include the later #45148D retainers. This sounds like the hyd pump issue with the really old pump using a seal instead of an "O" ring :shock:

You have 2 choices. Try to order the 251306R1 retainers and keep it original, or send me the bottom and I'll machine the bore to accept the newer 7/16 retainer.

Where's Don or Donny at?. They probably have encountered this before.

Hope this helps Chris,

Tue Sep 25, 2007 8:26 am

To clarify, the kit contained 3 seal cages w/felt seals. MY throttle shaft cage was the same as the replacement cage pictured and seemed to install ok. I might have driven it to far and have some cage distortion and I think metal to metal contact. I'm gingerly working on that. In a nutshell...the 2 choke shaft seal casting seats are SMALLER than the 1 throttle shaft casting seat(which I have installed already).

Tue Sep 25, 2007 8:32 am

Boy, do I type slow :shock:

Tue Sep 25, 2007 8:44 am

Boy, do I type slow
:? :?

Tue Sep 25, 2007 8:51 am


I had the problem of the dust seal covers being a kinda tight fit. Took a lot of messing with, but they did go in nicely after a bit. The other carbs for some reason didn't give me that problem. I may have one of the original R91 Carbs as well which certainly explains it. But I cannot be sure as the Part # is totally worn off :roll: :shock: :( :!: You may be onto something there..

Tue Sep 25, 2007 9:31 am

What a forum. You guys are great.

Tue Sep 25, 2007 3:51 pm

Probably a :shock: "Stupid" :shock: idea, but wonder if you could make the correct size retainers?

I was just browsing thru the local Mom & Pop hardware store for some things I need as I try to figure out another project, and came across "Nut Caps" there in the bin. Those are those "Top Hat" shaped little metal buckets that slip over the end of a screw or bolt.

Wonder if you could find a size close enough to work, and use something like that to make your own retainers?

The other 2 options I see that you have is to have it milled to accept the larger retainers. Or perhaps another brand carb uses that size?

Might try taking a trip to a lawnmower repair shop, and see if that size is used on some of the mower engines? Or maybe another brand of tractor?
Last edited by Into Tractors on Wed Sep 26, 2007 6:27 am, edited 1 time in total.

Tue Sep 25, 2007 5:01 pm


This is a new one for me. :?

It would seem that the retainers for the early carb are NLA. I think the only path forward is to machine the carburetor bottom to accept the newer retainers.

Good thing we have a first class machinist in the house. :D


You can order the seals and retainers separately to replace any that you may have buggered up. The retainers aren't driven to the bottom of the recess. Leave about a millimeter above the top of the recess.

Tue Sep 25, 2007 9:44 pm

First off...Thanks guys for the "leg work" trying to figure this one out.

Mike....This carb is off an early 47 sn 2752 so that holds up the R91,92 theory. I wonder if the whole carb is an R91 with the throttle cage and choke cage milled different sizes? I wouldn't think. More likely in the shop the 91,92 change in parts was going on and the assembler just grabbed what was at hand? Who knows!

Rudi...From what I can tell I don't think you could get the larger cage installed into a 91 bottom without totally distorting and splitting the cage or worse. At least from looking at mine.

Don....Are you positive the old retainers are NLA? I'd like to leave original if possible but doesn't sound good.

And ole Rick...I guess if the older retainers aren't available I'll take you up on your offer to "Mill Me" I'll give it a couple of days and see how this settles out and then come up with a plan.
Thanks again all