1952 8n running problem

[michael stewart]

My 8n has a fresh carb and all new ignition. It seems to idle fine and will rev fine if you move the throttle in neutral but under load it surges badly, when this occurs you can see the rod from the governor moving the throttle. Does this mean the governor is failing? Any suggestions?

 

[Bob]

Open the main jet a bit and see what happens.

 

[michael stewart]

Adjusting the jet made no difference.

 

[Dunk]

(quoted from post at 19:27:43 05/27/09) My 8n has a fresh carb and all new ignition. It seems to idle fine and will rev fine if you move the throttle in neutral but under load it surges badly, when this occurs you can see the rod from the governor moving the throttle. Does this mean the governor is failing? Any suggestions?

Tell me exactly what "fresh carb" means.

 

[Anonymous-0]

Does it help to choke it under a load,

 

[michael stewart]

no partial choke does not help

 

[michael stewart]

The carb was completely disassembled and soaked/washed in a carb agitator. A complete overhaul kit was install from yest's tractors.
needles were adjusted per the photo article of an overhaul on this site. Partial choke under load does not help and adjusting the main did not make any difference from 1 1/2 turns out to stumble(in 1/2 turn increments). I have been reading some other post on the forum and I plan to disassemble the governor to look for flat spots on the ball bearings this weekend. If that is not it I'll repost. If you have any other suggestions please let me know.

 

[Dunk]

(quoted from post at 20:27:33 05/27/09) The carb was completely disassembled and soaked/washed in a carb agitator. A complete overhaul kit was install from yest's tractors.
needles were adjusted per the photo article of an overhaul on this site. Partial choke under load does not help and adjusting the main did not make any difference from 1 1/2 turns out to stumble(in 1/2 turn increments). I have been reading some other post on the forum and I plan to disassemble the governor to look for flat spots on the ball bearings this weekend. If that is not it I'll repost. If you have any other suggestions please let me know.

My main suggestion for [b:88e67c401a]any[/b:88e67c401a] carb, is to have an air compressor, and a [b:88e67c401a]rubber tipped [/b:88e67c401a]blow gun, and be sure that you can blow thru every passage and orifice in it.

The rubber tip is so that you can be sure you are sealing off the end that you are applying pressure to.

This is done with the carb dissambled, don't try it with your carb assembled, you will crush the float.

Right now I need to do the one on my 4 wheeler.

 

[souNdguy]

that don't sound like flat spots to me.. hunting is usually fuel starvation...

got your fire order correct? 1-2-4-3?

soundguy

 

[Bruce (VA)]

Don't make the mistake of fixating on one solution to the problem.

For starters, you can check the governor w/o removing it.

There are three ways to check to check the operation of the governor. Get the throttle lever at it's lowest point (engine ideling) Then, start tapping the throttle lever slowly open. How far does the throttle move before the engine speeds up? Lack of low speed throttle response (like about 1/3 of the throttle) is the classic symptom of a bad or out of adjustment governor. Next test, put it in gear at about 1/4 throttle, put your foot on both brakes & let the clutch out. The engine should throttle up as the governor arm opens the throttle plate in the carb to compensate for the load on the engine. Next test, w/ the tractor running, pull on the rod going to the carb; does the governor pull back? If that does not work, get out the I&T FO4 manual & check out the 'adjusting governor' paragraph.

But, from your description of the problem, it's not your governor. The problem is fuel, either getting to the carb or in it.

Put a bucket under the carb, remove the bolt in the carb bowl & turn the gas on. Gas should run out in a steady stream as long as the fuel knob is on.

If fuel flow is ok, then adjust the carb.

Both Ford and Marvel/Schebler 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 anymore.

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)

3. Grasp the rod between the carb & governor & twist/shake it slightly; the slop in these rods often stops the adjustment cam from moving.

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.

If that doesn't work, it's time to pull the carb down again.

There are 6 things critical to a successful carb rebuild:

1. RTFM. Read The Freakin Manual....in this case, the How-To's on this board. If you don’t rebuild a lot of carbs, lay out each piece you remove on a clean shop towel so that you don’t lose the little screws/jets, etc.
2. Get the very caustic cleaner that comes w/ a wire basket from your local auto store & follow the directions.
3. Use a wire, welding rod tip or whatever it takes to clean every single passage. Be careful w/ the wire; you do not want to bore out the passages. If you do not have a set of gunsmith screwdrivers to remove the jets, be very, very careful. (this is an excuse to get a set)
4. Blow out every passage w/ compressed air (this is an excuse to buy a compressor, BTW)
5. Make sure both halves mate; use a straight edge.
6. Make sure the throttle bushing are ok before you start because most kits do not come w/ them. If you need throttle bushings, replace them or the tractor will never idle due to air leaking.


I'm gonna bet that you didn't do items 4, 5 & 6, right?
50 Tips

 

[michael stewart]

I did blow out the passages and check for play when I replaced the throttle shaft (it felt pretty good to me) and didn't think the bushings were bad. I did not check the body with a straight edge but do not have any leaks. I will try your carb adjustments and test the governor's reaction before taking it apart. Thanks!

 

[michael stewart]

I tried and have no throttle response in the first 3rd of the throttle range, it does not change until about 1/2 throttle.

 

[Tom in Aiken]

Michael - have you tried adjusting the throttle spring on the Governor linkage adjustment? (The one on the right side of the steering gear, not the spring at the governor.) See Figure 53 in the Owner"s Manual, pages 345 - 346.

As I recall mine 52 8N was doing the same thing and this adjustment resolved my issue.

 

[michael stewart]

I assume this would need to be tightened to account for stretch?

 

[Tom in Aiken]

Loosen the two nuts and move the sliding piece up and then down to find the right position - can't remember which one helped tighten the throttle but you can do this with the tractor running so you can get instant feedback on if the adjustment is making a difference.

 

[Kenster]

Michael, my first thoughts were just like SoundGuys. Fuel starvation, which will make the governor surge. When you were overhauling the carb, did you also clean out all three filter screens? The last two times I had symptoms like yours (governor induced engine surging) I simply removed and cleaned the round screen on top of the sediment bowl. I started there because it was the easiest place to start. And it immediately took care of the problem.
I would have next gone to elbow fitting between the fuel line and the carb.

If you haven't already done so, pull the drain plug and the carb and let it pee out enough gasoline to fill pint jar. If you're not getting a real strong flow, you've got a fuel flow problem somewhere.

 

[michael stewart]

I don"t have the f04 manual. I see the set screw on the governor. What is proper adjustment for the governor?

 

[IROCKWITHDIRT]

I just fixed a problem with mine that sounds exactly like yours. Fuel problem.

Junk in the center brass tube up in the tank/ on sediment bowl assy.

 

[michael stewart]

Fuel system is completely new except carb which has been overhauled. I installed a new head gasket and overhauled the governor this weekend. The balls looked ok but the race was pretty worn. I think someone cheated and just replace the balls it it's past life. I did richen up the carb just a bit and tightened the linkage (throttle quad to gov)I'm at 2 turns on the main jet and @ a turn and an 1/8th on the idle jet. NO MORE HUNTING!!!!! I was able to bush hog for 3 hours without any trouble. It does have what sounds like a misfire(almost a backfire but not loud) at idle but the valves didn't look the greatest when I had the head off. That might be a project for winter time. I think everyone was right on this one. Thanks for all of your input. Does anyone have a hint on what the ignition timing should be set at?