CA erratic spark

Carb thoughts. I am very happy with the carb function on our CA. ( note I do have to shut the gas off or it will flood). But the little Zenith carb was taken apart, soaked, and cleaned and it seems to work very well so far. I tend to like the Marvel carbs a little better for some reason. 

Interesting that the title of the thread was electrical and it changed into carb information. Not unusual for one or the other to be suspect.

Regards,

 Chris and Cheryl

It all started with my timing light.  I knew there were carb issues, but the timing light (digital not neon) still shows misfiring.  So I bought a fancy engine analyzer and it also showed misfiring.  Months later, after discussions with the vendor, they provided a software update that eliminated the misfire readings.  The spark signal sometimes doesn't go back to zero and so the analyzer (and presumably the digital timing light) was not resetting the trigger.  That's when I switched back to carburetor.  I had put a full rebuild kit in the TSX486 but there were several completely mangled jets that were nearly impossible to get out.  The very last one was recessed in a tunnel and the easy outs I could find would not fit.  I didn't want to mod the carburetor, so I finally sent it out for a rebuild.  Well, turns out, he couldn't get it out either without modding the carburetor (drilling the access port to a larger size).  But there was no change in misfire behavior when I got it back.  I attempted to find another TSX486 but was unsuccessful.  I did however acquire a TSX670 (which someone here said was compatible but isn't without quite a few mods).  It runs a little better with the modified TSX670, in fact as good as the zenith at idle.  It runs much better than the zenith in terms of responding correctly to sudden governor/load changes.  But it misfires more than the zenith at higher RPMs (so long as you only make slow RPM changes with the zenith, otherwise it completely dies).

So, I plan to go over the 486 one more time.  I have acquired extensive documentation now.  I've noticed a few potential issues that I need to check further but it may be a few months before I get to it now that I have the tractor usable again with the 670.  1) I see what appears to be microcracks in the bowl.  These are over the reservoir for the main jet.  I've not confirmed it.  2) the idle adjust needle in the rebuild kit is shorter than the original. I suspect the spring is compressing before it reaches the seat.  3) I suspect the idle seat is damaged given the damage to the original needle.  4) There is now no correct economizer jet installed (0.0775") after the rebuild.  Prior to the rebuild, a jet of that size was installed in the wrong position.  So I will try to get the right jets in the right positions.

I will also try to readjust timing and the TSX670 load/main adjusting screw to try to improve higher RPM performance.  If I get it working well, I'll probably leave the 670 installed but keep the 486 in working condition since it is the original.

I had switched to cleaning up the 2-14 plow this last trip.  I may have it cleaned/repaired and back together next trip.  Not finding parts for it, I had to weld one moldboard and one share.  I'm missing one moldboard extension and one draw rod.  I'm not too happy with the weld repairs and will continue trying to find replacements.  But it will be usable with the weld repairs.