Anyone had this before?

The short version is that cylinders #1, 3, and 4 purr smoothly, but #2 snaps and crackles constantly like it has a full race cam. No loud, and sudden bangs, but it is still disturbing never-the-less.

Here is the long version:
* It is being run on gasoline only
* When switching coil positions within the coilbox, the problem stays with cylinder #2
* All of the coils have been set at about 1.3 amp draw
* Hold down any combination of two coils with your finger, and the engine seems to run about the same rpm under each condition. However, whenever #2 is one of the cylinders that is running, the cackling is present.
* Machined the old commutator to get rid of the waves. No difference. Installed a brand new cast iron commutator and roller. No difference.
* Ran a new wire from the commutator to the coil box for #2. No difference.
* Completely isolated the #2 coil with it's own voltage source, wire from the commutator, and high tension wire to the plug. No difference.
* Changed the #2 plug wire. No difference.
* Cleaned the #2 plug, and then swapped with #1. No difference.
* Adjusted both the high and low adjustments to 1-1/4 turns outward on the Kingston carburetor. Waited until the tractor was warm, then set the high while at high speed, and the low while at low speed. They both ended up about where they started. No difference in the miss.
* Sprayed starting fluid all around the intake manifold near cylinder #2. No change in rpm. No differences in any other way.
* The cackling happens whether running off a battery or the magneto.
* As the rpm increases, the cackling blends more into the overall tone of the exhaust, and there is only the occasional miss.
* The aircleaner is a paper element. No water is used.
* There is no muffler of any sort on this tractor. Just a straight exhaust pipe that exits behind the differential.

I don't see how the piston rings could cause this, so the only thing left that I can think of is that carbon is on the exhaust valve of cylinder #2, or the exhaust spring may be weak. Thought about spraying a little water into the intake while running to break away the carbon.

Has this happened to anybody else?

Thank you,
Greg

The #1 cylinder exhaust valve spring looked funny so it was removed too. The problem was then found to be that one of the keepers was installed upside down! This forced the valve spring cap crooked and it, in turn, put a side load on the valve wearing both the valve stem and the guide. Not wishing to tear my Fordson too far down, I put it back together correctly to see what the engine would do. It ran so smoothly I left it that way.

You are right, I forgot to mention anything about the little spring contacts. What I did was to remove the nuts and completely remove the springs. I then wire brushed and sandpapered everything that could transmit electricity. The plastic that holds everything in place was then completely cleaned with alcohol to eliminate the possibility of electrical leakage to the surrounding coil box. Actually, after doing this, and still having the problem, is when I decided to completely remove the coil from the coilbox and connect it up electrically. This eliminated anything having to do with the coilbox or connections.

I did not have the engine apart, and have only owned this tractor for about two weeks. When it arrived at my house, it was a complete mystery to me. Was not even sure how to start it - if you can imagine that! There is good reason to believe that the engine was rebuilt not too long ago, based upon what I was told. The overall condition of everything that is observable, is good. The person who owned it died suddenly, and his brother sold it to me as part of settling the estate. The deceased person is well known for having things that are restored without regard for expense, and then preserving them under ideal conditions. So I have not torn the engine apart myself, and do not know first hand what it looks like inside. I will put together a way to test leakage with compressed air as you suggest.

As far as misfire vs uneven running, you may just have a point there. That is precisely why I mentioned that there is no muffler on the exhaust system. Perhaps the lack of noise reduction tends to exaggerate any unequalities from cylinder to cylinder. Again though, I have never heard a Fordson run prior to this one, and this may be completely normal. It is just that I am having a hard time accepting that three cylinders run one way, and the fourth runs another.

I have played with the Kingston adjustments to the point that I am satisfied that they are as correct as they are ever going to be. You are right, there is quite a temperature drop within the intake system. It really makes you think about the carb-ice problems that pilots have!

Thank you for your advice and help. Greg