I have a w115 240 D Mercedes 1976 model. It is smoking heavy under acceleration and if you rev the engine in neutral. It burns no oil inbetween oil changes. The injectors have been rebuilt with monarch nozzles. I adjusted the valves about 4 months ago when i purchased the car. I get about 25 miles per gallon. I drive 41 miles a day with half being highway miles going 70 miles per hour. I suspect that befor i purchased the car it was only driven occasionally in town for many years. The car has run smother and with more power over time. I guess this is due to the highway miles. It does not smoke at all during idle. Any suggestions what could be causing the smoke during acceleration? Thanks