Timing and plugs

[MisterCinders]

I've seen the answer somewhere before, but couldn't find it searching.

My plugs are a bit schizo, though the engine seems to idle and run well at low throttle. The pilot circuit chops still shows the plugs for 2 and 3 to be nice and tan, while 1 and 4 plugs keep coming up sooty and rich.

After some back and forth with the air/fuel screws, I wonder if the timing is slightly off, since the results are pairing up in step with the coils. I recall that ignition timing can show up in plug symptoms, but can't remember which direction to adjust things.

In other words, if the black plugs on 1/4 relate to ignition, should I look at advancing it or retarding it to correct?

TIA

[Killer2600]

Check timing with a timing light.

While retarded timing can lead to an incomplete burn it's not usual to make the plugs look rich and further it's more rare to occur on only half the plugs.

If timing is 180° from cyl 2&3 then it's where it should be and results from timing should be equal.

It's worth mentioning, the inner two cylinders heat up quicker and run hotter than the outer two.

[1948man]

Maybe one coil is not producing good spark. Have you tested the resistance of the coil that fires 1 and 4?