861 jittery timing

[William Fissell]

Thanks in advance

acquired a 861 that seems mostly ok but runs a little rough. I performed my routine new-to-me sanitary measures - rebuilt the carb, new points plugs rotor cap, and was working on timing. I often just time by how it sounds, but using a timing light showed a LOT of jitter in the timing mark. I noticed that the governor linkage was looser than my third girlfriend and Ive been tightening it. There a little slack at lowest RPM. I checked and the timing advance weights in the distributor are fine.

1. should the governor linkage be tight at all time, even at lowest rpm?

2. Other casues for very jittery marks?

thank you

 

[Jim L WA]

I don't know about the linkage, I don't have any manuals for that series, but as for other causes, I would check the distributor for worn bushings to start with. I don't know if that tractor had vacuum advance or not, but if so, a vacuum leak or an intake valve not sealing might cause that too.

 

[Destroked 450]

No vacuum advance on those tractors but worn bushing and loose timing advance weights and cause that issue

 

[William Fissell]

Followup: bad head gasket. Fixed.

 

[Jim L WA]

So the head gasket fixed the rough running I assume, but did it fix the jittery timing?

 

[William Fissell]

Yes indeed. It was juuuust a lil easier to set