8-N Carburetor

trying2mow · Aug 9, 2021

My 8-N is horribly finicky about choke position and needs to be run with it partially out. Tractor slowed to a crawl in the field. After tapping on carb (which sometimes helps) I noticed a little bit of gas dripping from a little screw at the base of my carb in front of the plug that drains the carb. Can any one tell me what this little screw is for and after tightening it up to stop leak..can't get tractor to even start? help!!

used red MN · Aug 9, 2021

You just completely closed the main fuel jet adjustment needle valve. Should be in the 2 to 3 turns out range from gently closed as in screwed closed. Some other Ford guy will chime in with final tuning procedures for it. Did you stick your fingers in light sockets before you knew what they were?

Edit: Sorry disregard, I jumped in thinking about most carbs the main jet is on the bottom of the bowl or at least most IH are. Some of those Fords are on the top in front angled down.

This post was edited by used red MN on 08/09/2021 at 08:11 am.

old · Aug 9, 2021

If it sort of sits at an angle that is the main jet cover screw and if screwed in to far it can close off the main jet. It is there so one can poke out the main jet with wire when cleaning the carb

wore out · Aug 9, 2021

(quoted from post at 07:57:55 08/09/21) You just completely closed the main fuel jet adjustment needle valve. Should be in the 2 to 3 turns out range from gently closed as in screwed closed. Some other Ford guy will chime in with final tuning procedures for it. Did you stick your fingers in light sockets before you knew what they were?

Red, a typical 8N carburetor has the main jet adjusting needle (Key #20) pointing upward at an angle from the TOP half of the carb.

Unless he has an oddball aftermarket carb he MAY have simply snugged up the little brass plug/screw, Key #5 in the parts drawing below (which would have no effect on the engine starting), but coincidentally something else may be wrong.

(Key#5 is used to plug a hole that was made at the factory for access to drill an internal passage, and has no function except to simply plug the hole left after the drilling operation.)

trying2mow · Aug 9, 2021

Thank you for responding but now I am not sure what to do. The little plug in no longer than about 3 mm. I noticed it dripping fuel so I just screwed in in tightly? Was the wrong? It seemed loose when I tightened it. Now the fuel is not leaking but tractor is no longer running. It tries to start but acts like it gets no fuel ? Did I mess it up when I tightened screw?

trying2mow · Aug 9, 2021

Thank you. So maybe I did nothing wrong by snugging the screw up? Tractor starts and dies like no fuel?? I had been having to jiggle the choke in and out to keep it running.

old · Aug 9, 2021

#5 can be remove to make it easy to poke out the main jet I've done it many times

Geo-TH,In · Aug 9, 2021

If I recall the adjustments on carb are backwards.

Screw 20 is main jet. Screw in to lean out fuel mix
Screw 13 is idle jet. Screw in and richen up fuel mix.

Try turning screw 20 CCW (out) and Screw 13 CW (in) and see if you have to run with
choke on.

trying2mow · Aug 9, 2021

Yes, it was the little #5 screw that was loose. Thank you. When I took carb off to inspect in and
found the loose screw, the linkage to gov just fell off. Would that have anything to do with it not
contin. to run once started?

trying2mow · Aug 9, 2021

Will poking wire in here unplug something? Does it unstick maybe a stuck float? Could a plug be causing me to fail to get gas to keep it running? What size wire do you use and how long?

JMOR · Aug 9, 2021

(quoted from post at 11:34:43 08/09/21) Thank you for responding but now I am not sure what to do. The little plug in no longer than about 3 mm. I noticed it dripping fuel so I just screwed in in tightly? Was the wrong? It seemed loose when I tightened it. Now the fuel is not leaking but tractor is no longer running. It tries to start but acts like it gets no fuel ? Did I mess it up when I tightened screw?

believe the answer is in how far did the plug go into the bowl. If the proper tapered thread plug, I expect ok, but if straight thread screw, the possibility of going in too deep & shearing the power adjust needle seat is a possibility that I have found before. See illustrations.

RogerinIowa · Aug 9, 2021

The screw may not be the correct one. If too long it causes problems like you are seeing. Shorten the screw just so it plugs the hole. Hope you have not damaged other parts.

old · Aug 9, 2021

To poke it out very well one has to remove the carb from the tractor so you can see into that hole. Poking it out might help open up the main jet but that is all it would do

old · Aug 9, 2021

The idle jet is the one that as you screw it in work backwards. The main jet you screw it out to make it richer

old · Aug 9, 2021

Only way you can screw that in and make it stoop it from running is if you have the wrong type screw in it. The one it should have will only go in so far before it get hard to screw in unless you force it

Geo-TH,In · Aug 9, 2021

Isn't that what I posted???

JMOR · Aug 9, 2021

(quoted from post at 14:33:12 08/09/21) Isn't that what I posted???

ither some don't read well or there is an echo in here!

old · Aug 9, 2021

I was in a hurry this morning and misread what you had said sorry

8-N Carburetor

trying2mow

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used red MN

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old

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wore out

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