Colt Case Ingersoll Garden Tractors

It seems so easy to buy a new carburetor when you come across a Kohler K321 14 HP engine in rough shape that you want to restore. There are plenty of cheap carburetors available for this engine, but as some of you may already know, most that you find are cheaply made in China. Their threads are metric so you won't be able to use carburetor rebuild kits made for the real carburetor, and the choke shaft lever is strangely shaped so that the choke function is reversed.

If you're happy to just have the engine back in running shape, this may be a perfectly viable solution. But what if you want to restore the old carb?!

My preference is to not throw out old parts just because it's easier to get a new part, when possible. Therefore, I will attempt to restore this old Carter #30 carburetor.

With the help of Smiley Green Wrench, it will be done.

There are "rebuild" kits you can purchase but they won't include everything you need to restore the carb to its former glory. One of the first things that need to be checked is throttle shaft wear. You've heard @ssmewing mention this already. Here's the throttle shaft of this particular carburetor. It's most likely to be have wear in the area circled in yellow, where the shaft is brighter from touching the housing. There is no bronze bushing set in the carb housing, so the housing, which is probably a aluminium or magnesium based alloy can incur wear more readily than the shaft which is steel.


For the record, the shaft measures 1/4" at the area of interest. It is supposed to be 1/4" too.




If either the shaft or the housing has excessive wear in that area, air will be sucked in and the air/fuel mix ratio will no longer be right. One way to test without disassembling the carburetor is to spray some starting fluid where the throttle shaft meets the housing while idling the engine. Safety first! Don't anything like that if you don't know how to handle very combustible gases.

In my case the shaft doesn't seem to have any significant wear. But what if the housing is worn out significantly where it meets the shaft? Here I try to move the shaft sideways to check for play.


https://vimeo.com/659102443






As you can see, there's very little play. Even so, if I want to improve the situation, what is the solution? The answer is bronze bushing.

Here's a view of where the shaft fits in the carb housing. Observe the recess area around the 1/4" hole where the shaft goes in. It is about 9/64" deep. Well, we can call it 1/8" though




The inner diameter of that recess area is 7/16"




One can find something called bronze thrust washers, made by Hillman. They are 1/16" thick, with 1/4" ID and 7/16" OD. Two of these inserted in the recess will give you the 1/8 thickness to fill the recess and provide a really nice bronze bushing bearing. Even more amazing is the fact that I found the item available in a pack of 10 on amazon and will be ordering it. I'm sure in the US it will be much cheaper and more readily available.



But I found a bronze sleeve bushing at a "local" store and will try to get it from them.

Timj wrote: ↑Tue Dec 21, 2021 2:57 pm With the help of Smiley Green Wrench, it will be done.

My wife insists that I use quality tools. My son reluctantly lent it to me

What did you determine was the difference between the old carb and the new one to make the linkage askew ?

Dave

DavidBarkey wrote: ↑Tue Dec 21, 2021 5:18 pm What did you determine was the difference between the old carb and the new one to make the linkage askew ?

Dave

Not yet Dave, that tractor is way in the back of the tent for now. Hopefully I get to it in the next few days. Will post an update then.

@DavidBarkey had a look today and no idea how but the link looks fine.



Maybe it was skewed when I first assembled it.

Back to the old carburetor. Got the one inch long bronze bushing from a bearing place just north of Toronto and cut a 1/8 piece. Hacksaw guys, forgive me for not using the lathe but the wrong chuck jaws were on and I was in great hurry having a few chores for the family waiting for me. After a little filing and deburring the bronze sleeve went in with a few light hammer knocks. It's a tight fit so I've no concerns it goes loose.




Inserted the shaft with a little grease in all the right places. There is zero side movement now, and the rotation action is smooth and precise. I deserve a beer!




But the housing looks pretty shabby, wouldn't mind stripping it of gunk and paint and giving it a new finish.

I'd say it also needs new gaskets, a good cleaning of all tiny holes and jet, etc.

It looks like hole in governor arm is to big to work properly

Eugen wrote: ↑Wed Dec 22, 2021 10:06 pm @DavidBarkey had a look today and no idea how but the link looks fine.



F783900E-56D2-4FA1-A71A-B423B62A949C.jpeg


Maybe it was skewed when I first assembled it.

I wonder now if it was just the camera angle .

Dave