Carb cleaning

BigTone · Jul 15, 2012

I have never cleaned/adjusted or rebuilt a carburetor before (I do have the service manuel), I was going to put a economy rebuild kit in because I have no idea what to look for and im not sure if I will clean it out correctly (carb is leaking bad, some have told me it could be varnish/dirt in the needle), couple questions:

Should I remove the whole carb or just the bottem bowl assembly?

Anything I should look for, any tips/tricks or dont do's?

How difficult is this?, I normally would give this one to the IH pros....

David G · Jul 15, 2012

I would soak the whole carb, rinse with water, then blow out ALL passages. I am in Eastern Iowa if you want help. I would wait to buy the kit until you find out if throttle shaft is worn and needs replaced.

Do NOT forget to put the venturi back in, it comes out.

David G · Jul 15, 2012

I would also replace the float when you have it apart.

Janicholson · Jul 15, 2012

Shut off the fuel! Remove the bowl. clean the bowl out with carb spray and set it aside. Look at the float. It should be hanging down at an angle. put a coffe can or pan under the carb and turn on the fuel a little. Fuel should run out of the area where the float pivots. Now while it is running out, lift the float gently with one finger till it gently stops. All fuel flow should stop. (just like a toilet tank float).
If very gentle pressure stops the flow, I would put it back together and give it a try.
if the float is heavy, it could have gasoline inside it, if it does, it is in need of replacement unless you are a very acopmlished solderer. If it is dry inside and the fuel still comes out when lifted, the needle and seat need to be replaced. The needle will probably have a Viton (rubber) tip. The old one may not. Be sure the little spring is correctly hooked on the needle, and the push plate of the float.
Next is float level. The specification is in the info in the kit. it can be done installed especially if yoy measure the distance of the old float, and get in mind how it needs to be to shut off the fuel. Jim

rustyfarmall · Jul 15, 2012

(quoted from post at 11:25:42 07/15/12) Shut off the fuel! Remove the bowl. clean the bowl out with carb spray and set it aside. Look at the float. It should be hanging down at an angle. put a coffe can or pan under the carb and turn on the fuel a little. Fuel should run out of the area where the float pivots. Now while it is running out, lift the float gently with one finger till it gently stops. All fuel flow should stop. (just like a toilet tank float).
If very gentle pressure stops the flow, I would put it back together and give it a try.
if the float is heavy, it could have gasoline inside it, if it does, it is in need of replacement unless you are a very acopmlished solderer. If it is dry inside and the fuel still comes out when lifted, the needle and seat need to be replaced. The needle will probably have a Viton (rubber) tip. The old one may not. Be sure the little spring is correctly hooked on the needle, and the push plate of the float.
Next is float level. The specification is in the info in the kit. it can be done installed especially if yoy measure the distance of the old float, and get in mind how it needs to be to shut off the fuel. Jim

There is no spring, or clip holding the needle to the float in an M carburetor.

rustyfarmall · Jul 15, 2012

(quoted from post at 11:12:22 07/15/12) I have never cleaned/adjusted or rebuilt a carburetor before (I do have the service manuel), I was going to put a economy rebuild kit in because I have no idea what to look for and im not sure if I will clean it out correctly (carb is leaking bad, some have told me it could be varnish/dirt in the needle), couple questions:

Should I remove the whole carb or just the bottem bowl assembly?

Anything I should look for, any tips/tricks or dont do's?

How difficult is this?, I normally would give this one to the IH pros....

BigTone, BEFORE you do anything, remove the fuel line where it attaches at the carb, remove the fuel inlet fitting (requires a 5/8" wrench), and then spray a BUNCH of aerosol carb cleaner directly into that hole. Put it all back together and if that doesn't fix it, get a little more aggressive with the thumping on the front of the carb. If that doesn't cure it, then it is time to open up the carb, OR send it off to a rebuilder.

The Red · Jul 15, 2012

I can verify that. I just opened up the M carb I bought last week and the needle fell out into the bowl. Do you assemble the haves back together on it's side to hold in the float needle? One in this carb is all steel and you can tell badly worn.

rustyfarmall · Jul 15, 2012

(quoted from post at 12:05:19 07/15/12) I can verify that. I just opened up the M carb I bought last week and the needle fell out into the bowl. Do you assemble the haves back together on it's side to hold in the float needle? One in this carb is all steel and you can tell badly worn.

If the float hinge pin is installed correctly as I have described in other discussions, the needle cannot fall out.

Yes, those all steel needle valves wear out. That is why all new needle valves made in the last 30 to 40 years have the "Viton" tip.

The Red · Jul 15, 2012

I will be ordering a complete kit from you along with a float and fuel strainer assembly. Just discovered the kit I have does not have the venturi tubes. Idle venturi is broken off just below the bottom bowl face. What size drill bit to drill it out without damaging the bowl threads?

TomH in PA · Jul 15, 2012

It's really not hard at all. Work on a clean hard surface or put something down on the floor in case you drop a screw or other small part.

Pay close attention to the float height, don't assume it's right just because you didn't change it.

rustyfarmall · Jul 16, 2012

(quoted from post at 12:55:33 07/15/12) I will be ordering a complete kit from you along with a float and fuel strainer assembly. Just discovered the kit I have does not have the venturi tubes. Idle venturi is broken off just below the bottom bowl face. What size drill bit to drill it out without damaging the bowl threads?

#40 (I think), but start with a smaller bit and work up. I'll also advise to not use a powered drill. Use a hand held chuck so you can "feel" if you are going straight. Also need a #4-40 tap.

For you machinists out there who know the drill should be smaller than the tap, yes, I know the rules also, but I just never could make that particular application work when doing it by the book.

The Red · Jul 16, 2012

I want to get that out first and make sure I don't ruin the bottom half, thus not needing a kit. I had to do that to an H carb but got lucky drilling it out.

rustyfarmall · Jul 16, 2012

(quoted from post at 08:50:07 07/16/12) I want to get that out first and make sure I don't ruin the bottom half, thus not needing a kit. I had to do that to an H carb but got lucky drilling it out.

That brass idle metering jet does not go all that deep. If you use the hand drill method, you will know when you are all the way through. There is plenty of hole left after the drill is through the idle jet, so there really is not much chance of going too deep.

sflem849 · Jul 16, 2012

(quoted from post at 11:22:29 07/15/12) I would soak the whole carb, rinse with water, then blow out ALL passages. I am in Eastern Iowa if you want help. I would wait to buy the kit until you find out if throttle shaft is worn and needs replaced.

Do NOT forget to put the venturi back in, it comes out.

Water!?! Never. Spray can carb cleaner. Water is a contaminate to fuel systems.

rustyfarmall · Jul 16, 2012

(quoted from post at 12:19:07 07/16/12)

(quoted from post at 11:22:29 07/15/12) I would soak the whole carb, rinse with water, then blow out ALL passages. I am in Eastern Iowa if you want help. I would wait to buy the kit until you find out if throttle shaft is worn and needs replaced.

Do NOT forget to put the venturi back in, it comes out.

Click to expand...

Water!?! Never. Spray can carb cleaner. Water is a contaminate to fuel systems.

I always rinse mine in HOT water, then blow them dry with compressed air. That is how I was taught in auto mechanics training way back in about 1971.

The carb cleaner that you soak a carb in is basically a high powered detergent. It NEEDS to be rinsed with water, just the same as you rinse your laundry or dishes after washing.

Dean Olson · Jul 16, 2012

I always flush carbs out with water after coming out of the chem
dip. I don't want to get that stuff on my hands.

I also use a pressure washer to clean out fuel tanks then flush with
the water hose, using dawn dish soap, till I have no debris or
colored water coming out.

sflem849 · Jul 16, 2012

Crazy, I guess I should change my ways. I usually go with spray carb cleaner.

I do clean fuel tanks out with my hot water pressure washer. I usually put some diesel in there to fight the rust right after that.

Carb cleaning

BigTone

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David G

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David G

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Janicholson

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rustyfarmall

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The Red

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