# 8N dies at idle



## KristofMI (Jul 7, 2021)

Long story short. I took the old carburetor and rebuild it. The main fuel needle was getting stuck all the time (yes gap set to 1/4" on the floater) and I had to use my screwdriver rubber handle to knock on the carb few times and it will release then. Anyway I needed the tractor that day and since my property is out of state I went and purchased the chinese carb from local tractor supply store. Mount it on the tractor and it won't stay running if I move the handle all the way down. It dies in like 2-3 seconds like it's getting out of gas. Someone suggest to check timing first because with timing out of adjustment I will have really hard time adjust the carb. So anyway lets assume the timing is correct. What should I do next? Adjust the idle needle or plate? Or something else?


----------



## harry16 (Dec 8, 2011)

You may have an air leak at your carburetor flange/seal or intake manifold flanges? With the engine running, spray some starting fluid on the carb flange and intake manifold flanges, looking for a change/increase of engine speed indicating a leak. 

I would back out the idle speed needle.


----------



## KristofMI (Jul 7, 2021)

harry16 said:


> You may have an air leak at your carburetor flange/seal or intake manifold flanges? With the engine running, spray some starting fluid on the carb flange and intake manifold flanges, looking for a change/increase of engine speed indicating a leak.
> 
> I would back out the idle speed needle.


Didn't think about that. Will try and report back.


----------



## Joe.S.AK (Nov 26, 2020)

About your old, rebuilt carb -

I had somewhat the same problem (actually more than just one) than you have on "Sally", my '40 9N. The replacement Chinese carb wouldn't get above a medium idle - so I installed the rebuild kit into the cleaned, old, cast iron, carb and re-installed it. Same sticking float / needle problem  so I pulled it again. Upon minute inspection I found where the side wall of the float area had, over decades, developed a slight, un noticed, "rust boil bump" which had, as it grew, slightly brushed against the float. I fitted a short, stubby straight steel wire brush (like a round parts cleaner brush) to the drill and carefully "chased" / cleaned / scraped the side walls of the float chamber.

*SHAZAM!*​
After washing / cleaning the carb body to remove the fine rust dust it worked 100% like new. Never a bit of trouble since.

The good news - those shiny Aluminum Chi-Com carbs *do* polish up well and with a little car wax they make a nice lamp for the shop. 
*:~)*​
- Joe -


----------



## harry16 (Dec 8, 2011)

Just in case you missed this point... On that carburetor, the idle jet is opposite of the main jet. To make a richer idle mix, you turn the idle jet IN.


----------



## KristofMI (Jul 7, 2021)

Joe.S.AK said:


> About your old, rebuilt carb -
> 
> I had somewhat the same problem (actually more) than you have on "Sally", my '40 9N. The replacement Chinese carb wouldn't get above a medium idle - so I installed the rebuild kit into the cleaned, old, cast iron, carb and re-installed it. Same sticking float / needle problem so I pulled it again. Upon minute inspection I found where the side wall of the float area had, over decades, developed an un noticed "rust boil bump" which had, as it grew, slightly brushed against the float. I fitted a short, stubby straight steel wire brush (like a round parts cleaner brush) to the drill and "chased" / cleaned / scraped the side walls of the float chamber.
> 
> ...


I might rebuild it again but this time I will use the old point. Old one have his tip red and more hard. New one the tip is black and it seems like it was covered in really thing rubber coat. I think this is why it's getting stuck in there. I will rebuild old one for sure I just need one that day and thought this will fix the problem righ away


----------



## KristofMI (Jul 7, 2021)

harry16 said:


> Just in case you missed this point... On that carburetor, the idle jet is opposite of the main jet. To make a richer idle mix, you turn the idle jet IN.


Okay. I think I saw that in manual.


----------



## Joe.S.AK (Nov 26, 2020)

"I will rebuild old one for sure I just need one that day and thought this will fix the problem righ away "

Christo, that is *exactly* how I ended up with my shop lamp.

- Joe -


----------



## KristofMI (Jul 7, 2021)

Been pretty busy lately. I had my carb rebuild buy a best guy for the job. He is rebuilding carb for Ford 8N. Right now the tractor runs much better then before but it will still die if I move the lever little bit more then half way down. I know carb is not the problem then. What will be the next thing to look for? Timing ? Governor?


----------



## pogobill (Jan 31, 2012)

A quick check would be to see if the governor rod is free to move. I would try and give it a go with the fuel cap loose to see if it might lead to a plugged gas tank vent. Then I'd check the screen in the fuel tank that is hooked to the gas bowl, up inside the tank, then check to see if the glass fuel bowl screen is littered with debris and rust. 
You can also disconnect the fuel line at the carburetor, with the fuel shut of at the tank, then open the fuel valve and see if you get a good flow...... catch the fuel in a glass jar 1) so you don't make a mess, and 2) so you can see if the fuel is relatively clean.
How old is the gas?


----------



## KristofMI (Jul 7, 2021)

pogobill said:


> A quick check would be to see if the governor rod is free to move. I would try and give it a go with the fuel cap loose to see if it might lead to a plugged gas tank vent. Then I'd check the screen in the fuel tank that is hooked to the gas bowl, up inside the tank, then check to see if the glass fuel bowl screen is littered with debris and rust.
> You can also disconnect the fuel line at the carburetor, with the fuel shut of at the tank, then open the fuel valve and see if you get a good flow...... catch the fuel in a glass jar 1) so you don't make a mess, and 2) so you can see if the fuel is relatively clean.
> How old is the gas?


I already checked the fuel flow and it's good. I checked the air filter inside and everything is clean as it should be. I disconnected the air intake to make sure it's not the problem. Gas is fresh. I don't put much in the tank. Just what I need and have a canister with fresh gas with me all the time.


----------

