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  1. #1

    Join Date
    Nov 2004
    Posts
    101
    Location
    Kearney, Missouri
    Tractor
    1952 Ford 8N

    Default 8N Carb Settings

    What is the correct setting for each of the 3 valves on an 8N (1952 model). A couple weeks ago, I took the carb apart to put in a new float and messed around with the valve settings. Just got it running again today...it ran pretty good for the first 15 minutes. Then, it kept acting like it wanted to die and was jerking on me. I tried it for another 10 minutes or so and it kept doing the same thing. It did seemed to run a little better when I pulled the choke out slightly...but it still jerked a little.

    I will get new spark plugs and see if that helps, but in any case I'd like to make sure the valves/screws on the carb are set correctly. I understand the setting may vary a little for each tractor, but is there a general rule of thumb to the settings?

  2. #2
    Elite Member
    Join Date
    Mar 2002
    Posts
    3,810

    Default Re: 8N Carb Settings

    If you are talking about mixture adjusting screws, there is no "correct" setting; however, 1 1/2-2 turns out is generally a good starting point for all mixture screws. Running better with choke on is a sign of a lean mixture, (not enough gas). Carb probably needs cleaning.

  3. #3

    Join Date
    Jun 2001
    Posts
    711

    Default Re: 8N Carb Settings

    Could be a restriction in the fuel lines up to the carb. Pull the fuel line off to the carb and see how the flow volume looks. If it's just a trickle may be clogged lines or tank outlet. Could also be fuel cap venting problem. When you pop the cap does it hiss/pulling in air? Did you get the float level set properly? Horizontal to a little angled up from horizontal to the base.
    Ditto on the settings, usually a good starting point....

  4. #4

    Join Date
    Nov 2004
    Posts
    82
    Location
    Lawrence, KS
    Tractor
    Farm Pro 2425, Ford 8N

    Default Re: 8N Carb Settings

    I have a '51 8N and have had it for 30+ years. I have had every bolt out of it at least once, over the years. Take your sediment bowl off, and if there is still a screen at the top of the bowl, make sure it's clean. And if it is and the tank is low on fuel, blow 20-30 lbs of air pressure back through the fuel bowl to the tank. The bad thing is people don't use the first half turn to three quarters turn for the reserve part of the tank, and it will plug up. Highly recommend using the reserve tank on the valve most of the time, to let any dirt/moisture go through the system. Like the other gentleman said - 1 1/2 to 2 turns on the main jet, 1 turn on the idle jet . With the fuel valve shut off (necessary on these old tractors, when not in use) you can take the low air pressure and remove both jet needles, and blow air back through the carb to remove any junk, but the problem is probably in the fuel tank reserve valve portion. Good luck - Yugo

  5. #5

    Join Date
    Nov 2004
    Posts
    101
    Location
    Kearney, Missouri
    Tractor
    1952 Ford 8N

    Default Re: 8N Carb Settings

    The attached drawing refers to the:

    -Main adjustment needle
    -Idle speed adjustment screw
    -Idle fuel adjustment needle

    Assume the 1.5 to 2 turns out refers to the main adjustment needle? Does 1 turn out apply to both the idle speed and idle fuel adjustments??

  6. #6

    Join Date
    Nov 2004
    Posts
    101
    Location
    Kearney, Missouri
    Tractor
    1952 Ford 8N

    Default Re: 8N Carb Settings

    Forgot the link...here it is. Ignore the colored arrows.
    Attached Images Attached Images

  7. #7
    Old Timer Soundguy's Avatar
    Join Date
    Mar 2002
    Posts
    51,669
    Location
    Central florida
    Tractor
    ym1700, NH7610S, Ford 8N, 2N, NAA, 660, 850 x2, 541, 950, 941D, 951, 2000, 3000, 4000, 4600, 5000, 740, IH 'C' 'H', CUB, John Deere 'B', allis 'G', case VAC

    Default Re: 8N Carb Settings

    Remember.. the main needle is out to enrich.. while the idle needle is backwards. I'd start 1 to 1.5 turns on each.

    Use the idle speed set screw to set your max idle rpms.

    I also agree.. if it needs some choke.. or stumbles on a quick acceleration.. may be a lean mix. ( or vacume leak.. )

    Soundguy

  8. #8

    Join Date
    Nov 2004
    Posts
    101
    Location
    Kearney, Missouri
    Tractor
    1952 Ford 8N

    Default Re: 8N Carb Settings

    Checked the float setting today. It was set more like .35 inches rather than .25 inches. I adjusted to 0.25. Will see if it runs better tomorrow. I will try to get the screw/needle settings figured out as well. Thanks for the info.

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