1970, 280SL Soot like particulate

[johnm]

 I have, what I would suggest, may be an excessive amount of black soot like particulate coming out my tail pipes. I especially notice it on my garage floor so know it is happening at idle. Inside the tail pipes is very black and sooty as well. Would appreciate any suggestions as to the cause and  fix. The car is otherwise running well but a little hard starting when cold.
 Thanks very much... John

[kampala]

johnm,

I think the reason you don't have a response yet is that your question has so many possible causes. 

If you search Running Rich, you should find lots of info.  The difficult part will be diagnosing why you might be running rich.  There are many possible causes, in addition you will need to isolate if you are running rich only when idling or at higher RPM's.   Here are a few causes to help guide you:

Cold Start Valve - leaking fuel.
Linkage Set incorrectly
Fuel Injectors Leaking fuel
Idle mixture set too Rich
Fuel Injection pump set too Rich for all RPM
Etc.

I would start with doing the linkage adjustment tour.  Then check the cold start valve.   This will get you started. 

Best of luck.

[johnm]

 Thanks very much for the response and advice. I'll get started.
John