Ford 861 Carb Tuning

[mcashatt]

Hello,

I recently bought this carb for my Ford 861:

https://www.external_link/FDS3578-Carburetor-new-not-rebuilt

It did not come with a manual and I don't know much about carbs. Can someone please look at the picture and tell me which is the idle screw, which is the main jet, and what the third screw is? I would also appreciate any tips for properly setting these screws. I have heard that they all get rotated 1.5 times out.

Thanks in advance!

 

[Andy Wickiser]

Link doesn't work, at least for me, maybe
try again or describe more completely. If
you purchased from a parts competitor to
this site link will probably be blocked.

 

[mcashatt]

Thanks for your reply. Hopefully the image comes through above. It was from Steiner. The part number is FDS3578 or C0NN9510G. Hopefully my image above works!

[/img:a8c4c05ff7]

 

[Andy Wickiser]

That's a Marvel Schebler copy probably of
a TSX813 or similar. Below is the Ford
general adjustment procedure. However
your power adjust is on the bottom, not
where shown as in earlier carbs. I would
probably first try without adjusting,
maybe it came with preset reasonable
settings. Also the procedure is not
particularly practical for the main power
adjust, I'd probably leave it at the
default unless you will be running at full
power routinely or it doesn't run well at
high power.

<IMG SRC=https://i.postimg.cc/zGgrLhfy/Card-Adjust.jpg>

 

[mcashatt]

This is great, thank you very much!

 

[ErnieD]

I found Color Tune, a spark plug with a window that allows observation of the combustion gases to be the most precise method of adjusting mixture.

 

[mcashatt]

(quoted from post at 15:10:23 10/17/23) I found Color Tune, a spark plug with a window that allows observation of the combustion gases to be the most precise method of adjusting mixture.

Thank you, ColorTune is very interesting. I am seeing both a 14mm and 12mm version for sale. Do you know which is the correct one for an old Ford tractor? Does it just go into one of the spark plug slots? Thanks again.