Hey there, so I just did some maintenance on my 41 9n. I cleaned up the distributor and put a fresh set of points, cap, rotor, and coil. When I got this done I needed to clean out the carb because it was clogged up with rust, so the carb was gone thru as well. So I fired it up today and it ran pretty well except for it surges a bit. It idles well and barely surges at full throttle, but just under full throttle to about mid-way it surges pretty bad. I checked for leaks at the intake and found none. To check if it was running lean I put the choke on a bit and it ran very rich- so I assume that's not the problem. I held the governor linkage and it ran nice and smooth. So could my problem be in the distributor? I would find it strange that my governor is acting up just as I did some work on other parts, but stranger things have happened. The engine is still producing good power- even while it was running like this I pulled a car out of the mud and it did not suggesting whatsoever. So- anyone have any suggestions?
 
probably clogged up again you said it had rust the rust came from the tank is the sediment bowl clean and with the fuel line off the carb do you get good flow, has someone added a inline filter that is a no/no they where never designed for a inline filter tank will need to be cleaned or replaced if it is still rusty and carb blown out again 👀
 
No inline filter. Tomorrow I will pull the sediment bowl off and clean everything out. The fuel flow looked pretty darn good today though, but since it's easy enough I will check the flow at the tank.
 
Think about what you said: "I held the governor linkage and it ran nice and smooth. So could my problem be in the distributor?"
 

If it ran nice and smooth when you held the governor rod, then the distributor is working as it should. I would think it was something in the arb. they are hard to get real clean.
 
Surging is a classic example of a lean air/fuel mixture. Have you fattened up the main fuel adjustment to see if it corrects the problem?

Assuming you have a M/S carb; the initial setting for the main fuel adjustment (down pointing screw on front) is 1-1/2 turns off the seat. After engine is warmed up and at full throttle, adjust for max RPM. Turning screw in will lean the mixture and screwing it out will fatten it up. If you have to turn it more than a couple of turns from the initial adjustment, you've still got trash in the carburetor.
 
As others are telling you, it's highly likely that you problem is an out of adjustment or dirty carb.

Try adjusting it first.

Make sure the tractor is at operating temp; that usually takes 10 ? 15 minutes at idle depending on ambient temp.

Both Ford and Marvel/Schebler (assuming you have a M/S carb ) say to set both the side-pointing idlemix and the down-pointing mainjet to 1-turn as a starting point. I set the down-pointing mainjet to 1-1/2 turns and don't fool w/ it until the final step.

Then adjust the side-pointing idlemix for fastest idle; not the smoothest idle. Next, adjust the behind the carb idle-speed set-screw for very slow 400-rpms idle. Do that idlemix adjust for maximum idle at least 3-times. Make sure that you turn the screws slowly, like 1/8 of a turn at a time & wait a second or two for the engine to catch up. Take your time!

Do it like this:

1. Adjust idle mix jet until RPM increases

2. Adjust idle-mix set screw until the engine nearly stops (as slow as you can get it unless you have a tach that tells you 400 rpm)

Repeat steps 1 - 3 three times.

Remember the side-pointing idlemix is out for lean, in for rich.

If you do not have any problems inside the carb, it is easy to get the idle down to 350 - 400 rpms.

Your last step is to go back to the main jet. Remember, in for lean, out for rich. If you end up turning it OUT more than ? turn for max power (remember, you already had it 1 ? turns out) then stop right there because you have a dirty carb or a fuel problem.

Lastly, each of us has his own definition of a carb cleaning. If your cleaning did not involve soaking the carb 24 hrs in a bucket of caustic carb cleaner & blowing out every orifice w/ a rubber tipped air gun, you didn't clean it, IMHO.
75 Tips
 
Well, sounds like I probably have a dirty carb still. Yes, I soaked it for several days in cleaner and blasted all of the passageways with the compressor. I have rebuilt many carbs over the years- from lawnmowers to 4 bbl carbs and have never had a problem with cleanliness. I wish my tractor had a tach (or proofmeter), because I know it's idling really darn low but I don't know if it's 450 rpm. I will clean out the carb again, clean out the sediment bowl & line, and check the flow at the tank. Not to argue, but if it was a lean condition would not have putting the choke on partially made it run better?
 
So have you tried adjusting the high speed needle?

If you pull the carb back apart, chase all the jets with a fine copper wire. Also look for an ill fitting gasket that could cause a vacuum leak. A vacuum leak will cause a lean condition.

I use an ultra sonic cleaner to clean carbs. Does a much better job than the environmentally friendly carb cleaner available now days.

Google Tiny Tach, they can be had fairly cheap. You may permanently mount it if you choose.
 
I used to use a ultrasonic cleaner when I had one available at my last job... it was very nice. I did try adjusting the main needle some, but it didn't really seem to do much. I suppose that also is a great indication that something is wrong with the carb! I thank you all for your imput, I have never had an issue before cleaning a carb- I am very meticulous.
 

[i:61720a175f]"has someone added a inline filter that is a no/no they where never designed for a inline filter"[/i:61720a175f]

in my experience, an inline filter works fine on an N. mine came with one and it hasn't caused me a bit of trouble. my fuel system passes the 2 minute pint jar test. it also does a better job of keeping rust out of carbs :)
 
Soooo, today I was messing with the tractor today. One thing I noticed is that it runs perfectly when the engine is cold... no choke on just a cold engine. After it has been running for a few min is when the surging begins. Next thing, while it is under load- such as just driving- it operates just fine. While holding the governor it runs just fine. If I pull the choke a little it runs crappy (as in rich) but the surge goes away. Here's a deal that makes me belive the carb has issues- I can adjust the main adjustment screw all the way out and even remove it and it runs exactly the same.

So, why would it run just fine while cold with no choke on and then start surging when it warms up? Why would the surge go away while driving (under a light load)?

Yes, I do plan on re-cleaning the carb tonight! It will be the cleanest darn carb EVER!
 
(quoted from post at 20:53:01 01/20/18) If you an remove the main jet needle and it runs the same, you have a problem in the carb.

I soaked the carb and just blasted it out- every passageway is clean and clean. I used a small high power flashlight and could see down where the main jet goes and looking thru the other side could verify that it is clear & clean. All other passageways were verified free and clear. So I dropped it back in the cleaner for another soak just in case. This time I will know for sure it's not a carb restriction. All jets and other parts will be double checked before assembly. So this time if I experience troubles it will have to be a vacuum leak or something else...
 
"Why is it a no no to add an inline filter?"

Welcome to the forum. A properly designed inline filter, meaning
one meant for a gravity fed, low pressure system isn't such a bad
thing. The wrong type of inline filter can be an issue.

Along with that is the fact that most people install them with
rubber hoses in the easiest to access point. Right next to the hot
manifold. One tug from a tree branch or similar and you could
have a fire.

Sediment bowls are old school, but they have the added benefit
of catching water in the bottom, when installed and maintained
correctly, which in line filters do not.
 
(quoted from post at 17:44:03 01/21/18)
(quoted from post at 20:53:01 01/20/18) If you an remove the main jet needle and it runs the same, you have a problem in the carb.

I soaked the carb and just blasted it out- every passageway is clean and clean. I used a small high power flashlight and could see down where the main jet goes and looking thru the other side could verify that it is clear & clean. All other passageways were verified free and clear. So I dropped it back in the cleaner for another soak just in case. This time I will know for sure it's not a carb restriction. All jets and other parts will be double checked before assembly. So this time if I experience troubles it will have to be a vacuum leak or something else...
Run a wire through all the passageways too. Air and light doesn't always cut it.
You mentioned jets. Did you mean the actual brass, replaceable, jets or are you talking about the adjustment needles?
 
Yes, I checked my throttle shaft bushings and they are good. By inspecting my jets and whatnot I was referring to the replaceable brass jets, and they are in great shape with zero grime or debris in them. Hopefully I will have time in the next few days to get this reassembled and see how she runs.

As far as the inline filter goes, no I do not have one. I have read that they can cause flow issues. However, I have an old 3 wheeler that has a gravity fed fuel system and I do have a inline filter on it and it works just fine. It is a filter designed for gravity fed systems and is not a paper element, it has a sintered bronze type element. I do not plan on installing one on my 9n, I think it's filter system is just fine.
 
Hey there... I was just getting back to working on my tractor. Still surging, only when warm. I read on a website that surging while warm can also be a distributor problem. So, since the carb was 100% cleaned and verified with wires thru passageway's and visually, I figured it wouldn't hurt to pull the distributor and play with it. So first off I have a set of the dreaded plastic rubbing block points, so I got a new set of echlin points. Next I found that my top bushing has some play in it. The bottom bushing does not have play. So I removed the breaker plate and the piece on the breaker plate that holds the bushing has significant play....( the rivets are worn out and not tight). So I figured I ought to buy a new breaker plate. Are the breaker plates sold on this Web site any good?
 
(quoted from post at 07:57:14 02/07/18) I have an assortment of guitar strings pieces I use to run through the passages.

:D What a great idea! I have struggled over the years finding pieces of this-n-that to clear various small passages like carb jets. Thanks for mentioning that.
 
I have some stainless TIG rod in .020 and .035. It works okay, wish it was just a tad more flexible... but it just takes some patience.
 
"Are the breaker plates sold on this Web site any good?"

Most of the new breaker plates are cheaply made. I would
tighten or replace the rivets and keep the original if possible.
The bushing(s) can be replaced.
 
I read on a website that surging while warm can also be a distributor problem.

I will be dazed and amazed if the distributor is causing it to surge.

My money is still on lean A/F mixture or vacuum leak which leans the mixture.
 
Well there, Dollarbill, I do agree with you. I know I have a set of junk points and bushing play, so I need to take care of it anyhow. However, we must have been thinking along the same lines since I ordered a set of new manifold gaskets yesterday along with a few other items. I'm hoping the manifold isn't too pitted, but I did read how to repair it if it is. The one think I do know is that darn carb is clean enough to eat out of!
 

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