Restoring a Kohler K321 carburetor

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Eugen Canada
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Re: Restoring a Kohler K321 carburetor

Post by Eugen »

Here's a screen recording of how I just did it.


https://youtu.be/6zGsrza9fIA


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Re: Restoring a Kohler K321 carburetor

Post by Eugen »

ssmewing wrote: Thu Dec 23, 2021 11:33 am Nice work, as a smack my hand to my forehead. :40: :40: :40:
I'm really glad you approve! :D
But, That is not where the new bushing goes. You are right the carb body is some alloy that is very soft. That is where the wear from the throttle shaft happens. Calipers are not used since there is no known spec for the acceptable wear which is actually the hole, not the shaft. You drill and add a bushing to the main hole.
I'd like you to consider a few things though. Sure, normally you drill the entire area of contact and replace it with the bushing. That repair to make sense needs a straight hole true to the hole on the other side of the housing. It's quite a risk to attempt that with a drill press. You also need a good reamer. The other thing is there are quite a few people that only used a smaller bushing like I did and the repair was successful. If the original carburetor worked fine for many years, with only a soft material in that position, this small bushing solution should also work for many years, don't you think so?

I showed calliper measurements in part to highlight the right size for the bushing, and in part to show that there is no significant wear on the shaft. Notice that I did not measure the wear on the hole, rather I showed a little video clip with the side movement. I do have a nice set of Oldak small hole gages and an Etalon 0-1" micrometer, but what would be the point? I think I already mentioned above that the side movement was so small that most likely the carburetor was going to work just fine without the bushing, but I felt like doing this repair anyway and I'm pretty sure I can get many years out of it.
The correct repair is all over the internet if you use Google, with pictures, and everything. Sorry if I seem harsh. I am the older guy and why I am the one who uses Google and has to tell young people to use Google kind of baffles me. Maybe I should try Google on that.
I honestly want to know why you consider the repair I did incorrect.
I recently replaced the rear brakes on my beater with a heater. A very easy job that I have done many times. But, the first thing I did even before ordering parts was to watch a YouTube by a professional that usually is hosted by the parts sellers. What this does for me is if there are special considerations I know them. The good videos that I look for I actually take notes from. The good videos tell you the wrench or socket sizes you will need. Then at the end, the good video tells you the torque specs for each fastener. If it does not then I Google the specs. It's all free and easy and should be your number one step.

Now it turns out I also have to the front ones. The price of owning a 20-year-old vehicle that lived a dirty life. The front bleeders were barely anything left. The rear calipers were completely not working. So, on to the fronts.

The rear disk had one of 2 pistons not frozen. All sliders were locked up. It was making some noise in the rear end.

I seem to be blocked or not allowed from posting pictures or attachments.

https://photos.app.goo.gl/J68CBfJddUjpDdoz9

My truck is only 14 years old, but the previous owner didn't maintain it very well. I know what you're saying about getting good info on the internet. My default is to use the service manual for my truck which does have all the correct torques and procedures, but it does tend to be terse in places you need more details, so for one job (timing belt replacement) I did watch a good youtube video. This is the work I've done myself so far on it: replaced catalytic converters (major pain because of the tight area), oxygen sensors, valve adjustment, timing belt and everything that was in that area, like water pump, idling pulleys, tensioner, etc., serpentine belt, parts of the AC circuit piping, fuel injectors, fuel pump, radiator, xfer case fluid, transmission fluid, rear diff fluid, rear brake disks and pads, front pads, AC clutch, and most recently the alternator. From double digits long term fuel trim values I got it to near zero, and no more codes thrown. Now the power steering pump whines I think, and I'll probably replace it soon. My point here is that I think I know where you're coming from regarding life with an old car.

:cheers:
Case 224, 444, 644, 680E
Kubota B26 :blush:
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Re: Restoring a Kohler K321 carburetor

Post by DavidBarkey »

I personally do not like Utube videos as an instruction tool . There is no way to know if the information is correct , and if it is false or misleading the maker is not held accountable . There is no way to inter act with the maker if you are unsure about something . Most people assume if it is on the the internet it is correct . I prefer manuals, put out by the makers ,diagrams , tips and tricks from forums like this where you can bounce things of others back and forth . Now that been said , the internet is repository full of information both good and bad . Sifting through it can be the biggest challenge at times .
My 2 cents , you may keep the change

Dave
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Re: Restoring a Kohler K321 carburetor

Post by Timj »

DavidBarkey wrote: Sat Dec 25, 2021 7:19 am I personally do not like Utube videos as an instruction tool . There is no way to know if the information is correct , and if it is false or misleading the maker is not held accountable . There is no way to inter act with the maker if you are unsure about something . Most people assume if it is on the the internet it is correct . I prefer manuals, put out by the makers ,diagrams , tips and tricks from forums like this where you can bounce things of others back and forth . Now that been said , the internet is repository full of information both good and bad . Sifting through it can be the biggest challenge at times .
My 2 cents , you may keep the change

Dave
I do use YouTube and other internet videos as a convenience thing, but I never go with the info from just one. It is generally a educational thing, then I decide if I'm comfortable with tackling it or do I go looking for more info. Manuals are always first. I've picked up some good tips, but some info is so off. :O

Sometimes for entertainment I sit and watch well and pump videos, as it's my business, but in the end I end up feeling so sorry for people that have received and followed so much bad information. :headbash: I don't comment, I should, but there are not enough hours in a day. :35:
:creeper: deck's on, blades sharp, let's go it's time to mow :48: :446cart:
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Re: Restoring a Kohler K321 carburetor

Post by Jancoe »

There are many ways to skin a cat. Just because it's not your way dosent mean it's not gonna work. I think the repair will work just fine. I have a hard time trusting youtube guys also. Lots of mis information floating around out there.

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Re: Restoring a Kohler K321 carburetor

Post by ssmewing »

Eugen wrote: Fri Dec 24, 2021 8:56 pm
ssmewing wrote: Thu Dec 23, 2021 11:33 am Nice work, as a smack my hand to my forehead. :40: :40: :40:
I'm really glad you approve! :D
But, That is not where the new bushing goes. You are right the carb body is some alloy that is very soft. That is where the wear from the throttle shaft happens. Calipers are not used since there is no known spec for the acceptable wear which is actually the hole, not the shaft. You drill and add a bushing to the main hole.
I'd like you to consider a few things though. Sure, normally you drill the entire area of contact and replace it with the bushing. That repair to make sense needs a straight hole true to the hole on the other side of the housing. It's quite a risk to attempt that with a drill press. You also need a good reamer. The other thing is there are quite a few people that only used a smaller bushing like I did and the repair was successful. If the original carburetor worked fine for many years, with only a soft material in that position, this small bushing solution should also work for many years, don't you think so?

I showed calliper measurements in part to highlight the right size for the bushing, and in part to show that there is no significant wear on the shaft. Notice that I did not measure the wear on the hole, rather I showed a little video clip with the side movement. I do have a nice set of Oldak small hole gages and an Etalon 0-1" micrometer, but what would be the point? I think I already mentioned above that the side movement was so small that most likely the carburetor was going to work just fine without the bushing, but I felt like doing this repair anyway and I'm pretty sure I can get many years out of it.
The correct repair is all over the internet if you use Google, with pictures, and everything. Sorry if I seem harsh. I am the older guy and why I am the one who uses Google and has to tell young people to use Google kind of baffles me. Maybe I should try Google on that.
I honestly want to know why you consider the repair I did incorrect.
I recently replaced the rear brakes on my beater with a heater. A very easy job that I have done many times. But, the first thing I did even before ordering parts was to watch a YouTube by a professional that usually is hosted by the parts sellers. What this does for me is if there are special considerations I know them. The good videos that I look for I actually take notes from. The good videos tell you the wrench or socket sizes you will need. Then at the end, the good video tells you the torque specs for each fastener. If it does not then I Google the specs. It's all free and easy and should be your number one step.

Now it turns out I also have to the front ones. The price of owning a 20-year-old vehicle that lived a dirty life. The front bleeders were barely anything left. The rear calipers were completely not working. So, on to the fronts.

The rear disk had one of 2 pistons not frozen. All sliders were locked up. It was making some noise in the rear end.

I seem to be blocked or not allowed from posting pictures or attachments.

https://photos.app.goo.gl/J68CBfJddUjpDdoz9

My truck is only 14 years old, but the previous owner didn't maintain it very well. I know what you're saying about getting good info on the internet. My default is to use the service manual for my truck which does have all the correct torques and procedures, but it does tend to be terse in places you need more details, so for one job (timing belt replacement) I did watch a good youtube video. This is the work I've done myself so far on it: replaced catalytic converters (major pain because of the tight area), oxygen sensors, valve adjustment, timing belt and everything that was in that area, like water pump, idling pulleys, tensioner, etc., serpentine belt, parts of the AC circuit piping, fuel injectors, fuel pump, radiator, xfer case fluid, transmission fluid, rear diff fluid, rear brake disks and pads, front pads, AC clutch, and most recently the alternator. From double digits long term fuel trim values I got it to near zero, and no more codes thrown. Now the power steering pump whines I think, and I'll probably replace it soon. My point here is that I think I know where you're coming from regarding life with an old car.

:cheers:
I have been around the forums for some time and even read decades of posts that happened before I was on the forums. That is how I learn and that is all I needed to graduate with honors in college even. No notes, I read it understand it, and move on.

Yes, you must have a drill press and a drill press vice to open and set the carb on, and the drill press must be corrected squared. But, no you do not drill two holes, you only drill the top hole. The bottom hole is a blind hole. No, you do not need a reamer as the hole will get a bushing. So, it does not need a precision cut to the hole. Then you are now using a very small contact with the throttle shaft which is softer than a bronze bushing.

Once you put a full bushing in the hole where the throttle shaft originally makes contact you will never need another bushing. The only thing that will need eventual changing is now the throttle shaft. Yes, I have done this to a carb that came to me with a bushing but a worn shaft. But, I guess I do not know if the shaft was replaced during the bushing install.

I am not talking about theory. I repair these as a hobby that pays for my hobby. I have done at least 20 of these repairs and have seen on forum posts spanning many decades others doing the same repair. I have at least 2 bushings and 2 new shafts in my parts bin at all times. I advertise through Craigslist that I will do this repair.

This is the correct bushing. https://www.mcmaster.com/catalog/127/1303
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Re: Restoring a Kohler K321 carburetor

Post by Eugen »

The bushing from McMaster-Carr is indeed superior. I also agree that a larger contact surface area is desirable all things being equal. Not sure how you concluded that 841 bronze is harder than the shaft which must be some sort of mild steel. You could harden the shaft a little if you really wanted to.

That being said, if I did this repair for someone who paid me I'd probably aim for the best solution.

But what if the smaller surface area of a lesser quality bronze bushing allows it to wear faster than the shaft? It then becomes a maintenance item easily replaced every 2-3 years. Cheap too.
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Re: Restoring a Kohler K321 carburetor

Post by ssmewing »

Eugen wrote: Sat Dec 25, 2021 1:15 pm The bushing from McMaster-Carr is indeed superior. I also agree that a larger contact surface area is desirable all things being equal. Not sure how you concluded that 841 bronze is harder than the shaft which must be some sort of mild steel. You could harden the shaft a little if you really wanted to.

That being said, if I did this repair for someone who paid me I'd probably aim for the best solution.

But what if the smaller surface area of a lesser quality bronze bushing allows it to wear faster than the shaft? It then becomes a maintenance item easily replaced every 2-3 years. Cheap too.
I have replaced a couple of shafts in carbs that had the bushings. So, experience is the answer. The way that the vibration of the engine shakes against the governor set up I think is what starts the problem. I have seen Onan engines with 10 times the hours and the throttle shaft is just fine.
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