My 1978 300CD smokes sometimes, otherwise it runs really well except for burning some oil between oil changes. I have not changed injectors, it has about 160k, any thoughts? I have had a bunch of "experts" look at this around San Francisco, nobody can really troubleshoot the issue.

 

I have adjusted valves and changed filters, I have owned the car for about 10 years. I want to change the injectors? It has decent compression according to Sal in SF. How about injection timing? tired injection pump? Sometimes it runs without smoking. Thanks for your support

 

You have not said when it Smokes and what color the Smoke is so it is hard to comment further on the smoke.

At your Mileage if you still have the Original Injectors I would say it is time to rebuild them.
Unfotunately the made in India Bosch replacement Nozzles for the Injectors don't have a good record of quality control or longivity.
That leaves the Made in German Monark Nozzles and the Made in Italy Bosio Nozzles.

If you buy the rebuilt Injectors sold by mose of the Parts Places you are going to get the Bosch Made in India Nozzle and it is likely their Pop/Opening Pressure will not be well balanced compared to each Injector.

If you purchase your Injector Nozzles separately and have them rebuilt by a Fuel Injection Shop or a skilled person that has an Dieslel Nozzle/Pop Tester it will cost a little more. But, Fuel Injection Shops try to do a better job balancing the Injector Pop/Opeing Pressure.

This will give you some Idea what is involved in Injector Rebuilding. I disagree with the Authors choice of what to lap the precision parts with. You should have a Lapping Plate for that or next best is a piece of Glass to sub for the Lapping Plate.
How to Rebuild Injectors
vincewaldon.com - HOW-TO: Rebuild Diesel IDI Injectors

Of coures your Fuel Injection Pump Timing should be done just as a matter of a normal tune-up.

You can also check your Camshaft Timing by lining up the marks Ecaxtly that are behind the Camshaft Gear and the Camshaft Bearing Tower mark. Look down at what the Crank Damper Pointer points to and note the Degrees.
When it came from the Factory it was timed at OT (top dead center on the Comression Strok).
The degrees reflect the change of Camshaft Timing due to Timing Chain Stretch and Gear Wear.

However, there is a more accurate test for that called the 2mm Method.

 

Thanks 911, I wish I knew a good mechanic who could help me with the timing in or around San Francisco, do you have any recomendations?

 

I live way south of SF and no one works on My Cars but Me.