Looking for a little advice on the timing numbers I just pulled from my 73’ Duster (backfire issue)

Mattax said
Small changes in timing wouldn't effect it (exhaust) so directly or obviously.
Too much timing will cause a gurgling or pinging sound under load. Under heavy load (full throttle) this is real bad and need to get out of the throttle immediately. You can look at the spark plug porcelain for bits of aluminum - that would be sign of detonation under load.

Too advanced for the conditions can contribute to excess NOx which is sort of brownish. I just think that's unlikely. It would ping or at light throttle, trailer hitch (feel like the car is getting jerked ).

What color is the exhaust smoke and under what situations do you notice it? White? Brownish? blackish? bluish?

It seemed to be very dark grey. It was a hot day yesterday and it didn’t start happening until after it was warmed up. Then it continued throughout the day. Also went to a car show and it happened on startup too but I think the engine was still warm.

My idle also was rough when this was happening. It had dropped about 200 rpm’s in drive and sounded like it was struggling.

I did run seafoam through the tank and carb last week but I thought I had got all that out and that was more white. I bought a new pcv valve and breather just to see what happens. Both those hoses seemed for the most part clean.

I ran it today and didn’t notice smoke or rough idle (it was slightly cooler). Driving me crazy.