Zenith vs IHC Carb

[Old Tractor Fixer]

I am new to the site and have checked but don't see this addressed. I have 47 cub. I has had a Zenith 13794 replacement carb installed. We recently got the tractor. It had been doing some snow plowing in Colorado. Looks like the carb was new in 2002 per the tag. The problem is it starts a little hard. Then when warm I can get a real nice idle but when you rev it up or drive it was white fuel smoke out the stack and just about chokes the driver. I also tends to fowl the #1 plug. Is this somehow jetted for high altitude and we are now running at sea level? Is it the wrong carb? My research shows the proper Zenith would be a 13781. Should I just order the new IHC that is available or is this one easily fixable?

[redfin]

The typical carb would have been the 3/4" IH updraft . The Zenith came along later and are somewhat cold natured from my experience. I am sure you will gat answers on the sides oif the fence on this one.

[Rick Prentice]

Welcome Old Tractor Fixer to the site.

but when you rev it up or drive it was white fuel smoke out the stack and just about chokes the driver

Alot of members have replacement Zeniths on their cubs. Some run fine, some run alittle on the rich side. Sounds like yours runs rich. We did a test on carbs a couple years ago, on the dyno, between the Zenith and the IH carb on a cub of your vintage. The IH performed better on that cub. I also know IH made changes to the IH carb and some of those run different than other IH's, so I guess what I'm trying to say is-- it may take some adjusting with any carb you install. Maybe some others will be along to give some pointers or their views.

I see Jim beat me to the punch

Again, welcome to the site and keep posting,

Rick

[Lurker Carl]

Welcome to the wonderful world of Cubs!

When only one spark plug is fouling, the symptom does not indicate a carburation problem. The carburetor would coat ALL the spark plugs with excess soot. When only a few cylinders are having such problems, look for ignition (tune up) or internal mechanical problems. Since the tractor is new to you, start with a complete tune up and include a valve adjustment and compression check. You may as well start with a clean slate and get the parameters reset to manufacturer's spec before trying specific repairs.

White smoke is water vapor. Black smoke is excess fuel. Blue smoke is oil. Your description is that of water, common in cold weather due to condensation but it should not keep blowing white smoke after the engine reaches operating temperature. Once again, a tune up will help correct, or narrow down, the problem by eliminating the most common causes of poor performance.

[Tim Martin]

My Zennith carb always ran rich no matter how much adjustments I made. Nevertheless, it still ran good but you could smell the unburt fuel in the exhaust - it's better than running lean I guess.

[Jerry M]

WELCOME Old Tractor Fixer.

[BigBill]

Welcome to the forum !!!!!! When we all have problems the heavy hitters here will chime in and bail us out. Its a good thing because were else would we go to repair these awesome machines.

I agree with the above posts i would check the ignition wire, compression and the valve adjustment on the cylinder with the fouled plug first. I would also clean out the holes in the distributor cap too with that special wire brush thats made for that. I've learned that a bad connection between the cap and ignition wire will make 1 cylinder not perform correctly too. If the cover on the wires aren't sealed moisture can get in there and rust will form making it so the juice won't flow to the sparkplug. I learned this the first time by going thru the whole fuel and gas system before i noticed it was the ignition wire.

Does the white smoke smell like anti-freeze? That could be another problem.

I have noticed on my tractors i will get some blue smoke on start up but then it will clear. But if i use it everyday it won't smoke at all. I figure its from not being run enough. These tractors been sitting a longtime idle with newer engines before i got them. I don't think there broken in yet.

On my zenith carbs they all have the block off plug on the high speed jet. So its non adjustable. If the carb is too rich i wonder if the adjustable needle setup from another zenith carb will work on our carbs so the high speed jet can be leaned a little? I guess they set the zenith carbs a little rich to play it safe. But since these are water cooled engines they can run a little leaner. You could also adjust your sparkplugs too by going to a hotter heat range too. Cold plugs do tend to foul. If we had a bad cylinder that was prone to fouling we would change that one plug to a hotter one.

[Lurker Carl]

Just in case you didn't know already. Cub owner's manuals, parts manuals and GSS-1411 Blue Ribbon Service Manual are available on-line via the "Manuals" link at the top of each page on this website. I suggest you also order hard copy reprints from a company like Binder Books, nothing better than having information in your hands for some pillow reading.

[Rudi]

OTF:

I am new to the site and have checked but don't see this addressed. I have 47 cub. I has had a rZenith 13794 eplacement carb installed. We recently got the tractor. It had been doing some snow plowing in Colorado. Looks like the carb was new in 2002 per the tag. The problem is it starts a little hard. Then when warm I can get a real nice idle but when you rev it up or drive it was white fuel smoke out the stack and just about chokes the driver. I also tends to fowl the #1 plug. Is this somehow jetted for high altitude and we are now running at sea level? Is it the wrong carb? My research shows the proper Zenith would be a 13781. Should I just order the new IHC that is available or is this one easily fixable?

I just googled Zenith 13794 and 13781 Carburetors, cause I am not used to Zenith's. Probably only have seen a couple, but.. nonetheless.. I found that these two carbs are essentially interchangeable ( ) as the same kit is used for both. Wether or not the jets are the same, is still up in the air.

Carburetor Rebuild Kit - Farmall Cub - Zenith #13794, 13781
Year Range: 1958 - 1977
Catalog Number: FP24102

Should be some useable links in the Google search though.

So.. now to the good stuff

First, to the greatest forum on the internet, and to the Cub Family. You will find that all the folks on this forum are kind, helpful and just full of Cub info and knowledge. They also happen to be the finest folks I have ever met

The Welcome Wagon is a relatively brief introduction to the information that is currently available on Cub tractors, and answers many of the common questions new members ask right of the bat. Although it is a bit overwhelming , it has been designed to actually be copied to a Word Processor such as Microsoft Word (which preserves the active links), and saved to your desktop for easy reference at a later date or when you have a bit more time to read all the information contained in the links below. Please do so, enjoy and I hope this will be a useful aid in learning more about your New Cub Tractor

Filling out your Profile is a real help. It just needs to be - State,City, County, a lot less than what is available in your local phone book. Knowing where you are will help in members offering to come help, when you are looking for parts - the area that would be useful to you etc., Also our CubFests, Mini-Fests or a simple KaffeeKlatsch/get together over coffee and a doughnut etc., to help each other benefits. Just a thought

When adding signature lines to your profile, the use of animated or non-animated banners and large graphics files must be avoided. These files consume large amounts of bandwidth and cause slow page loading, especially for those forum members using dialup connections.

Ok, so here is the spiel :

I would suggest that you read this thread: New Members and Visitors, Please READ Prior to Posting. There are many great links to informative pages such as the ATIS FAQ's 1 and ATIS FAQ's 2, The Best of H.L. Chauvin who has written very interesting articles on troubleshooting common problems with your Cub. One of the other projects we have been working on and it will be a continuing effort is the The Cub Book of Knowledge. This the the place to go to get all the quick links to some very good articles written by many members of the forum on solving some of the problems we encounter as we repair, maintain and up-grade our Cubs. Keep looking for this to grow.


Also, you might want to visit the Cub Manual Server as there is tons of info on servicing, maintaining and re-building your Cub. In addition to this basic information, there are also a number of other useful tools available on the server. There is the Specialty Services page which has contact info for neat stuff like getting your seats recovered, buying quality Decals, Serial Number tags and a host of other neat items. Also there are the Parts Pages - both Used Parts Suppliers and New Parts Suppliers pages with links to quality dealers. I am always looking for YOUR favourite dealers for New and Used Parts to include here. These pages are intended to complement our Official FarmallCub.com Website Sponsors:

• JP Tractor Salvage
• Ralph's Cubs
• TM Tractor Parts
• Kub Kraft

I would also recommend that you visit Binder Books and purchase the three most important manuals you can own for Maintenance, Repair and Rebuilding your Cub. These are the Owner's Manual, the GSS-1411 Service Manual and the TC-37F Parts Manual. Although they are available on the Cub Manual Server, it is better if you also have your own paper copy. Binder Books is the only Authorized IH Publication Reprint House and they have the best quality manuals available. Most other's are not of the same quality. Just a personal thought here, the I&T Shop Manuals, although helpful in some areas, really are not sufficient for the job. If you wish though, they are good additional reference works.

IF you really want to get the skinny on all things Cub, might I suggest you get a copy of Ken Updike's Farmall Cub and Cub Cadet's . While you are at it Original Farmall Cub and Cub Cadet is Ken's latest addition to the series. Along with Guy Fay's Letter Series Originality Guide, these are three must have's in anyone's collection.

In addition to the above information, don't forget to check out the various articles that are available to help with your Repair, Restore, Rebuild or just your Maintenance Projects. There are a number of sub pages such as Electrolysis or Rust Zapper's, Maintenance Tips, Jigs and Techniques, Implement and Part Sketches and of course the Paint, Decals & Other Finish Questions which has the Paint Chart and the Paint Committee Decisions links.

Oh, and while the program still lasts.. you might want to check the Announcement: Navistar Free Gas Cap Offer - On-Line Form thread at the top of the Cub Forum and send away for the new style safety cap before that program runs out as well. The program has been extended and no new definite end-date has been announced at this point. It is an extension only and may end rather quickly depending on available stocks. Please do take advantage of this offer and get the new safety caps

I truly hope that you enjoy your Cub and that you will be a frequent contributor to the forum. Again, to the Cub Family

[Old Tractor Fixer]

Thanks for the info. The exhaust definately smells of unburned fuel, no sign of and anitfreeze smell. Smoke is a light white haze, not billows. All plugs soot up some just #1 fouls 1st.

[Rick Prentice]

OTF, If you rule out the suggestions from the other guys, and find yourself back to the issue of the newer Zenith carb supplying just alittle more gas than your older cub needs, here's something else to think about before you spend any money. If you do a search back in the archives, you'll find that the original IH carb that went on the early cubs, like '47,(I think it was the R1 version) had some smaller/different internal parts, like smaller diameter choke shaft/seals, discharge nozzle was drilled different, main jet orfice was smaller,not sure about the idle tube or main bleed orfice, etc. If you buy another IH carb, it may work great on your cub, but there's still a chance it may run a tad rich and not be the exact carb needed. It'd be great if you knew someone who would allow you to put their IH carb on your cub just to see how different it runs, but you still might have different results from the next one you try.

Don't give up, and keep us "up to date" on your findings.

Rick

[Old Tractor Fixer]

Well I finally got the cub running right. I checked the basics, Plugs, compressions, etc. everything checked out. I found the plugs were hotter so it had this problem for awhile. I pulled the Zenith carb I didn't find anything wrong but found screwdriver marks inside so someone had been chasing this at the carb before. At this point i decided the Zenith was a lost cause. I bought a rebuilt IHC carb from Farmallcub It now runs great. In addition it looks 100% better. It was worth the price just for howmuch better it looks.

Thanks for all the input from everyone.

OTF

[Old Tractor Fixer]

I made a mistake in last post. I got the IHC rebult from Farmall Parts.com.

OTF

[DanR]

Interesting point about the jet size. I grew up in Colorado and a 'high altitude' tune up was necessary. I mainly consisted of a smaller main jet and advance the timing 2 deg. It had to do with the thinner air. Most car dealers would make the change before the car was sold. Now it would be difficult to find an old carb man and various size jets.

[rickguns]

Welcome to the best forum on the net!