My 1985 380 Having failed at 3.6g/mi with a limit of 3.0 NOX I am trying to adjust timing these are my initial readings.

2 deg retarded at idle without vac adv cold
7 deg advanced with vac cold
I took these to check the temp advance

when hot
10 deg adv at idle w/vac spec range is 13-19 deg
30 deg adv w vac at 3k rpm spec range is not specified

25 deg adv without vac at 3k rpm spec is 25 deg at 3k

My question is that I had it in the shop and they were to retard the timing to make it pass the test. The idle readings are retarded but the high speed settings are not.

I realize there is centrifical advance taking place should I set it back to 20 deg advance at 3000 rpm without vacumn?

Is there a reason why the idle settings are retarded below spec range and the higher rpm are not?

Thanks for any help provided I realize I am new here, learning a lot and the ropes in where to post things.

__________________
Bob

1985 380SL 110k,mi
2000 Harley Dyna Conv 29k,mi
2004 Honda Element 48k,mi
1999 Honda Accord EX 156k,mi
1984 380SL 90k,mi (gone)