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Farmall & IHC Tractors Discussion Forum
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w-4 carburetor adjustment

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jcarter

04-12-2006 06:00:52




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just getting this tractor running after being seized up for the last 10 yrs.It starts up and runs smooth but at fast idle needs about 3/4 of the choke on.Faster engine speed, a little less choke.I cleaned the carb all out, but do I still have a passage plugged?I don't know what the proper adjustments are either.Or could I have a air leak at carb to manifold gasket?I used the old one for now to get it running,in case I did have to take it apart again.It was a good looking gasket thu.

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jcarter

04-12-2006 10:04:20




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 Re: w-4 carburetor adjustment in reply to jcarter, 04-12-2006 06:00:52  
Thanks for the advise.I'll check my adjustments first and go from there.Forgot to say that I did have the tank steamed and sediment bowl all apart to clean, and a new inline filter put on for any loose stuff still in tank.I didn't know the adjustments so may be that or a passage still plugged.The carb. was pretty dirty when I took it apart.It seems to be running lean. Will these "passages " cause that or a rich condition?

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P Backus

04-12-2006 16:48:42




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 Re: w-4 carburetor adjustment in reply to jcarter, 04-12-2006 10:04:20  
I didn"t know that you had an in-line filter installed. How much fuel did you put in the tank?
Some people love those in-line filters, but I know at least one person who is taking it out because it causes just a little bit of restriction in the flow, and if there"s not enough fuel in the tank, it won"t run to the carb fast enough.
Paul



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Bob M

04-12-2006 10:41:37




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 Re: w-4 carburetor adjustment in reply to jcarter, 04-12-2006 10:04:20  
Plugged passages in the W4 carburetor will always cause a LEAN condition.

One exception: A plugged air passage in the idle circuit will cause a slightly rich condition at idle. Also with a plugged idle air passage adjusting the idle mixture screw (or even removing the screw completely) will have no effect on how the engine runs.



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P Backus

04-12-2006 09:20:14




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 Re: w-4 carburetor adjustment in reply to jcarter, 04-12-2006 06:00:52  
What the others said is good, but I just wanted to add that if you take the carb drain plug out and turn the gas on, it should run out at a pretty good clip, not just dribble out. That"s after the initial gush of gas from the bowl is out. If it doesn"t run out fast enough, then there is a little bit of rust or something partially blocking the line. Take the gas cap off and look in the tank to the outlet on the bottom to see if you can see somethintg there. Don"t use compressed air to blow back through the carb, as you will collapse the float- been there, done that. Also clean inlet screen where the fuel line goes into the carb.
Also, in case you didn"t know, the high speed mixture fuel screw is the one on the bottom of the carb at an angle. The idle mixture air screw is at the throat of the carb, with a spring under it.
Paul

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Wayne Swenson

04-12-2006 06:53:36




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 Re: w-4 carburetor adjustment in reply to jcarter, 04-12-2006 06:00:52  
With the engine warm & running at wide open throttle (WOT), turn high speed mixture screw in until the engine begins to starve for fuel. Then turn the screw out until the engine begins to blubber. Now find the "sweet spot" in between the two settings. If you are working the engine (plowing, etc.), then the high speed screw needs to be turned out 1 turn or more beyond the "sweet spot" to be sure the engine isn"t starving for fuel and can develop its rated power.

The same procedure can be followed for idle mixture with the addition of the ldle stop screw to set the low speed RPM.
On the "H" W-4 carb, the idle mixture screw is an air adjusting screw so turning in will richen the mixture and out will lean the mixture.
Aren"t carbs fun!!

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Bob M

04-12-2006 06:47:32




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 Re: w-4 carburetor adjustment in reply to jcarter, 04-12-2006 06:00:52  
Most likely a plugged carb passage or the high speed mixture is set WAY too lean. However other possibilities are the float level is set to low or there is a restriction in between the fuel tank and the carb inlet (plugged screens in the sediment bulb or carb inlet)

It's probably NOT a bad manifold gasket leaking air - if it was the problem would be worst at low idle.

Suggest cleaning out the screens, then dropping the float bowl (lower half of the carburetor) and thoroughly cleaning the passages/orifices again. Be looking for a gob of rust, piece of gasket, etc caught in a passage at the bottom of the bowl or in the main discharge jet. Poke through each passage with a piece of stiff wire or similar. But be careful not to scratch or otherwise enlarge any of the orifices!

----

My experience is high speed mixture settings vary widely from tractor to tractor. They seem to vary anywhere from about 1-1/2 to about 5 turns open.

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