Farmall Cub

Guys:

Gord Trail has a very nice 48 Cub that has been lovingly redone. Notice I said redone and not restored to factory - that way no correct police will be involved



His tractor is not a working tractor at the moment, but is primarily a show tractor. Some on the board have seen it at CubFest Northeast 2004. A very pretty tractor it is.

We have been trying to figure out a problem for months now and have yet to quite get it solved.

In 3rd at anything above 1/2 throttle, she surges like crazy.

Surging can be caused by a improperly set governor, a sticky governor, a sticky rod etc.

Surging can also be caused by dirt in the fuel and blockages in the screens, main jet, or any of the passages in the carb.

Right Or am I still missing something

Gord has had his tank done, the gas is clean as can be expected. Not even a hint of dirt particles in the fuel bowl. The screens are clear, both orifices in the main jet are clean and clear, the float is set properly, needle and seat hve been done... you name it, it has been done.

The governor was rebuilt by a very knowledgeable man who does restorations for 2 of the areas largest collectors (boy do they collect farmalls ). Gord and I replaced the bumper spring as it was not responding as it should.

It appears that all is working properly. We just cannot eliminate the surging. I have read, re-read and re-read the manual ad infinitem on this subject and I just cannot seem to find the answer to the problem.

I think I need some fresh thinking on this. The only thing I can think of is the rpm's - either to high or too low (hence the question on tachs on a mag ). Outside of that, I am flustered.

Thoughts gentlemen please

Rudi, do I understand correctly that this only occurs in 3rd gear?

Yup:

First and second she runs like a top! Weird I know.... but that is what is happening.

Rudi,
I know you've been through it but it sounds like a fuel delivery problem to me. I am by no means an expert but I would try a little choke when it starts surging and see if it helps. I had the same problem with my 55. It would run fine in 1st and 2nd but to try to take off in 3rd it would surge.

RPM changes would be more severe in high gear so the governor tends to work harder to correct. I would consider replacing the governor spring and the bumper spring. Would also again go over the linkage looking for binding or sloppiness.

Fella's I know this is going to sound like some off the wall advice but not to long ago I had a similar problem, thought it was gas, Govener, then carb. Turned out to be the Coil. I don't know if this will help, but when I red this I felt the need to put my two cents worth

BD:

Bumper spring is brand new right out of the box and is working well. Governor responds as it is supposed to.

One thing you did point out though was as I suspected, the governor is a slave to rpm changes and in high gear it will be very noticeable. So, gonna check rpm's now that y'all helped me figure it out..... which I should have known. Unfortunately, when your mind is on a specific track, it can sometimes not see the obvious

Donny:

I will try that. If the choke evens it out, then we will go through the whole system again and try to find out the reason. It is probably going to be painfully obvious once we discover what the cause is.

FJ:

I really doubt that it would be the coil. I know even brand new can be defective, but as it is an internal and has never caused any other problems, I would rule it out. Ifn however we still cannot find the problem after checking the other two ideas, then I guess we will have to have a look at that. -- Donny get ur thinkin cap on

All have said very good & smart ideas.
Rudi,
You said you did not think it was the coil maybe not.
But is the spark advancing as it should.
This will make the gov. go nuts as gov. will try to adjust for a slow or no timing curve( or should I say over or under compinsate)know that is not spelled right....

Dale:

Will recheck timing as well the next time I go over. Thanks