Advanced timing will give you more smoke, more power, and at lower speed, better milage. When the smoke appears, you will be getting less power for the fuel burned.

Sounds as if you are right on target for milage, though -- I get 31-32 consistantly with light AC usage, less in town and with heavy AC -- it is in the 90's here with high humidity, so the AC compressor never shuts off in traffic. Milage only varies a little -- lots of heavy accleration and/or grade climing will reduce it some, but in general diesels don't show the same decrease in milage in slow traffic that gas engines do. I get about 29 in the Volvo in town, but never more than 33 on the highway. Disappointing, as it has a 2.4L motor (105 horsepower, 145 ft/lbs torque).

I've gotten the injection timing screwed up on the Volvo -- lots of smoke and no power at less than 2000 rpm. The timing is a huge pain to set on this engine (belt driven pump, off the back of the camshaft with a friction driving gear ------!) and I think maybe the valve timing is off, too -- this weekend's project.

A young friend of mine asked me how much power my 87 had yesterday -- told him I thought it could out-do his roommates "new" '79 Ford pickup. I didn't realize I could outrun him, too!

If it were me, I'd set the timing back to 15 ATDC to eliminate the smoke -- diesel particulates are nasty.

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!