Carburetor help

[BSFlyBoy]

I have a 1955 Cub with a leaky carb, imagine that, right? The carb does not have any markings on it and I'm not finding anything that looks right so that I can order a rebuild kit. Can anyone identify it for me?

[BSFlyBoy]

So, in the list of possibly related posts I found the link to the pictures and can see it is a Zenith. Would this be original on a '55? What/where is the best rebuild kit?

[Don McCombs]

You are correct in identifying it as a Zenith. It would not have been original to a 1955 Cub. McDonald Carb & Ignition is an excellent sources of parts and rebuild kits for this carburetor. http://www.mcdonaldcarb.com

[Glen]

Hi,
Cubs came originally with an IH carburetor, until mid 1975, when IH changed to the Zenith carb.
Someone changed yours to a Zenith carb.
The Zenith name might be on the engine side of the carb.

Below are pages from the Cub parts manual, showing the Zenith carb. It shows the engine serial number when they began using the Zenith carb.

Below is some info for servicing it.

Clean it well before taking it apart, that keeps some of the dirt out of it.
When apart, soak it in carb cleaner, if you have that, or use carb spray in it, and blow out all passages with compressed air. Use your safety goggles when using the air.
Be sure to clean the main jet, number 20 in the parts pic, it screws out of the carb. You need a screwdriver that fits it well, they have said on here to grind one to fit, if you don't have one.
The main jet is under the plug, number 18 in the pic.

http://www.farmallcub.info/manuals/cub_ ... 012-14.jpg

http://www.farmallcub.info/manuals/cub_ ... 012-15.jpg

When you have the float off it, check and see if it feels light, shake it gently some, it should have no gas inside it. If it has gas inside it, or it is in poor condition, it needs a new float.

Set the float height accurately.
Below is a page from the Cub service manual, showing the float height, for the Zenith carb, in the lower right pic on the page.
Usually the float drop needs checking, I don't see in the manual pic that it gives a measurement for it.
I don't have a Zenith carb to look at.

http://www.farmallcub.info/manuals/gss- ... 002-09.jpg

The original angled fitting where the gas line connects to the carb has a filter screen in it, be sure the screen is clean.

TM Tractor, at the bottom of the page, has new parts for Cubs, and Zenith carbs.
The new needle and seat they sell has a small clip that goes on the end of the needle, and attaches to the float, to pull the needle open when the float goes down.
I don't think the Zenith carb had that in the past, it is not in the parts pic.
It has probably been added so the needle doesn't stick closed.

Below is a pic from TM Tractor of the original IH style carb that a 1955 Cub came with.

[staninlowerAL]

Ditto on McDonald Carb.

[BSFlyBoy]

Thanks for the info. Curious if there is any reason to go back to an IH carb?

[Don McCombs]

Only for originality's sake. If it functions well, I'd just leave it. It is a part of the history of that particular tractor.

[BSFlyBoy]

Several choices on the Zenith rebuild kits, any idea on the model?

[Bob McCarty]

There is usually a round or rectangular tag attached to the top that has the model # on it.

[BSFlyBoy]

Yeah, I think the tag is missing. There is a 2-98 stamped into the base flange, but I don't see anything else. I'll remove it and see if something is on the backside.
Another question, I have a suspicion that the base flange does not actually match. Is it safe to assume the flange barrel should flow smoothly into the carb?

[Glen]

Hi,
It looks like in your pic the manifold and carburetor flanges are the same size.
The Zenith carb has a bigger flange than the IH carb, and manifold for an IH carb had.
Your manifold has probably been replaced also, since the flange is the same size as the carb has.

Your pic doesn't show the manifold much, another pic would be helpful.

The listings for parts for a Zenith carb at TM Tractor don't show you need any model number, they only have parts for the Cub carbs. Their website is at the bottom of the page.
Below are their carb parts, the Zenith parts are down the page, in the 6th line.

http://www.tmtractor.com/new/fl/fl_001newparts.htm

[BSFlyBoy]

Finally home and working on the tractor some more. Got the rebuild kit from McDonald, seemed decent. Rebuilt it but have not tried to start it yet. You will all enjoy the one picture....
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IMG_20200707_210336981.jpg

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[Bob McCarty]

Did you not get the oversize manifold gasket? I'm not sure that what you show will seal.

[BSFlyBoy]

That was from before I rebuilt it. Someone put the small gasket on it. If you look closer, the gasket bore was too small as well and it caught the butterfly and bent it. A couple of well placed taps on the anvil and it's good and flat. Whomever rebuilt the carb last time tipped every piece of brass in the carb. Looked hideous, but I think I have it straightened up. Grabbing a tune-up kit tonight and should be running in the morning.
Someone asked me to post the manifold picture, I'm assuming it is not original to a '55?

[Glen]

Hi,
The manifold looks like it has been replaced with the newer style. I don't know if you looked at the intake hole in it, above the carburetor. The Zenith carb has a 1" bore, I think.
The IH carb has a 3/4" bore.

Below is a listing at TM Tractor showing a new manifold for the IH carb.
The originals looked the same, but had no IH emblem, or part number where they are in the pic, that I know of.

http://www.tmtractor.com/new/ae/418fp.htm