A Missing Cub

[newpoint101]

I have a missing problem with my 1956 Cub.

The cub with start immediately and run ok for maybe 15-20 minutes then it will start to miss and buck. If I release the mower deck and take it out of gear it will start to run smooth. If I put the mower back on it will run ok for a few minutes and then start the miss and buck routine. If I shut the Cub off for 10 or 15 minutes the same routine as above will happen again (run ok and the later start to miss and buck bad).
I have changed the coil, rotor, points, plugs, spark plug wires. After no avail I took the Cub to a local mechanic and he cleaned the carbeurator and timed the unit and he tested the Cub and said it is fine.
It worked ok for about 2 weeks and the old habit is back. I think he has exhausted his knowledge and it would do no good to bring it back I think.
Any suggestions to try next.

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[kinelbor]

Check the vent holes in the gas cap. If they are plugged then after a while a vaccuum will build up in the tank and fuel will stop flowing.

[Rudi]

I have a missing problem with my 1956 Cub.

The cub with start immediately and run ok for maybe 15-20 minutes then it will start to miss and buck. If I release the mower deck and take it out of gear it will start to run smooth. If I put the mower back on it will run ok for a few minutes and then start the miss and buck routine. If I shut the Cub off for 10 or 15 minutes the same routine as above will happen again (run ok and the later start to miss and buck bad).
I have changed the coil, rotor, points, plugs, spark plug wires. After no avail I took the Cub to a local mechanic and he cleaned the carbeurator and timed the unit and he tested the Cub and said it is fine.
It worked ok for about 2 weeks and the old habit is back. I think he has exhausted his knowledge and it would do no good to bring it back I think.
Any suggestions to try next.

newpoint101:

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

Boy does that sound familiar. I would normally suggest that you check you plugs make sure they are not fouled. Then check the Vent holes in the Gas Cap.. then check the Fuel Delivery System to the Carb - ie -- go through the Sediment Bowl, clean and repalce parts as necessary. Then on to the carb... read the threads below.. then go to the Server and look up Lurker Carl's Carb Fixes... I know you said all of this was done, but just because you were told all was up to snuff.. make sure for yourself.

After that is done, you may want to go through your Governor.. this may be where to problem lies.. in the load system... check linkages from carb to governor, make sure all governor linkages are freely operating and respond to input.. it really does sound like a loading problem..

Usually it is related to those issues. If that doesn't solve it, you may want to look at the aspiration system.. Oil bath filter.. the breather line from the filter to the front of the crankcase.. make sure that it is not plugged either..

I am sure the others will pop in with a few suggestions as well..

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.

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

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 is 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.

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

[Bus Driver]

I suspect a bit of debris in the high speed jet. It is the 3/8" brass hex head in the side of the carburetor. Shut off the fuel, removed the jet. Clean it with smooth wire and compressed air. The tiny hole in the end is the actual metering point. I use a 10X magnifier to examine those jets. I found one with flake of rust lodged in the hole. The rust swiveled about just like a throttle butterfly and caused all kinds of symptoms, including some times when the tractor ran fine.

[Cecil]

Good advise from everyone. I've experienced the gas gap causing a vacuum in the tank many times. It's one of the first things I check when I have a similiar problem.

I was worried for a minute when I saw missing Cub in the title. I thought the Big Dog was out running again.

['Country' Elliott]

Hey Cecil MY FRIEND...You're readin' my mind! When I saw the TITLE of this post my FIRST THOUGHT was "BIG DOG'S done stealthed ANOTHER ONE"

B.T.W."Newpoint101"...Check your sediment bowl & screen for any dirt from the gas tank that may be restrictin' your fuel flow to the carbuerator when your Cub's under LOAD

[Bigdog]

Well, when I saw the title I knew I was gonna get blamed!

All that aside, try adding some Marvel Mystery Oil to your gas. 15 to 20 minutes is just long enough for valves to get hot and start sticking. and, if you haven't adjusted the valves it might be worth the effort.

[Rudi]

Well, when I saw the title I knew I was gonna get blamed!

All that aside, try adding some Marvel Mystery Oil to your gas. 15 to 20 minutes is just long enough for valves to get hot and start sticking. and, if you haven't adjusted the valves it might be worth the effort.

BD:

I did that.. added some MMO to my gas. Ever since Ellie has been acting strange.. won't stay running. I have been thinking maybe I have to rebuild that carb.. but that doesn't make a lot of sense either..

Before adding the MMO.. mostly as a PM as all recommend.., Ellie ran and ran and ran, just like the EveReady Bunny... now.. she sounds more like a sick cat...

Ideas

[Bigdog]

How much did you add?

Check the plugs to see what color (colour) they are. And look at the quality of the spark.

[Rudi]

Well, approximately what it said on the bottle...

I have a gut feeling that there is too much, and that it is fouling the plugs.. I was sort of thinking I would drain the tank, flush with another 1/2 gallon, then run real clean gas through and see if that would fix it up..

I think what I did was add according to crankcase... which would be too much.. it is these old eyes of mine.. they don't quite as well as they used to, especially that super small print on the bottles...

Spark is real strong.. best it has been in a long time..