47 cub carb question

[dambrino1]

Hello all, I have a 47 cub with a worn out carburetor. This cub came with a couple of carburetors and we’ve even tried a rebuild kit but still having problems.Looking at buying a new one but I see there are many options of course. Steiner parts looks the best but very costly. I see there are also cheap carbs too. Not sure what is the best/cost affordable option. Hoping you guys can give me some insight?



Thanks!

[Don McCombs]

What leads you to believe that your carburetor is worn out? The vast majority of Cub carbs can be made serviceable with just a good cleaning and maybe a few minor parts.

[Eugene]

Place a help wanted ad in the "The Vine, classsified". If the carburetors are IH or Zenith, there are several folks on this site who rebuild carburetors.

[PFord]

Having just rebuilt my own Cub carburetor, I can confidently say there's only a couple of parts in it that would be subject to any wear that would affect how the tractor runs. The fuel inlet needle, the float or float assembly, and under extreme circumstances maybe the idle tube. There just isn't anything else in it to "wear". The shafts that the two butterflies ride on and their packing can wear, but that wouldn't make the tractor run differently.

What are the symptoms you're seeing?

[dambrino1]

Thanks for the reply guys. I think the carburetor was probably assembled using various parts from other carburetors, which isn’t a bad thing, but I just don’t really know what I’ve got. So I was kind of thinking about just buying a new one and starting from scratch. But, on the other hand it was running good at the beginning of this year and now I can’t get it to Fire. The carb leaks fuel in various places. I completely disassembled it cleaned everything reassembled, and still can’t get it to act right. All needles, juts, and parts seem to be in good condition, Soon as I put fuel to it starts flooding in pouring out the other side.and from the bottom?

[PFord]

Thanks for the reply guys. I think the carburetor was probably assembled using various parts from other carburetors, which isn’t a bad thing, but I just don’t really know what I’ve got. So I was kind of thinking about just buying a new one and starting from scratch. But, on the other hand it was running good at the beginning of this year and now I can’t get it to Fire. The carb leaks fuel in various places. I completely disassembled it cleaned everything reassembled, and still can’t get it to act right. All needles, juts, and parts seem to be in good condition, Soon as I put fuel to it starts flooding in pouring out the other side.and from the bottom?

Those symptoms really point to a failed inlet needle, a bad float, or a float out of adjustment. It's the job of the float and inlet needle to stop the flow of gas when the carb is "full". If it's overfilling, it's likely the fault of one of those two components.

That said, neither one of those things would cause a no-start condition.

Can you post some photos of where it's leaking from?

[Eugene]

Now I can’t get it to Fire.

Check ignition.

[Don McCombs]

Let's start with your desire to give up on the existing carburetor and buy a new one. The OEM carburetor is no longer available. The are two common reproductions currently available. The first is assembled in the USA from multinational parts. It is rather expensive, but good quality. It typically works well right out of the box. The second one is assembled in China from China made parts. It is a little more than 1/10th the cost of the USA assembled carb on eBay. But, it can have issues out of the box. The float is frequently not set properly. Also, there have been issues with one of the air bleed holes not being drilled completely. Both of these issues are fixable by the average home mechanic. If you opt for a new carb, the choice is yours.

You say that you disassembled the carburetor, cleaned it and reassembled it. But, we don't know whether it had all the properly functioning parts and gaskets installed before you began. There is a brass part that is mounted into the carb top called an idle tube. It is easily broken and we don't know whether it in still intact. Perhaps you could post a photo of each of the two halves for us to look at.

If all is in order there, my suggestion would be to start simple, by adjusting the float in accordance with the diagram below. That adjustment is a trial and error process of slightly bending the float mount arm and/or the stop tab until you achieve the proper settings. The float drop dimension is 1.6 inches with the carb top positioned in the upright position. The float lift dimension is 1.4 inches with the top positioned in the upside down position. Maybe a little confusing, but give it a try. Then reassemble the carb, put it back on the manifold and try to start the tractor. There are further adjustments to be made. But, we can worry about that later.

Also, it wouldn't hurt to read through all the carburetor and fuel related posts in the How-To Forum before you start.

P.S. Note that the float dimensions are taken with the gasket NOT in place.