Unlike Rotary Fuel Injection Pumps like are used on GM, Ford and VW type Diesel Engines there is no timing mark on the mounting flange of the Mercedes Fuel Injection Pumps.
Also changing the timing only changes when the fuel is delivered not how much fuel is delivered.
Starting Fluid can damage your Engine so I would avoid using it again.
Go down the list and find "Drip Timing Threads"
Diesel Injection:
Besides Drip Timing there are other methods of timing the Fuel Injection Pump but they involve buying some a special electrical setup.
If you are having a fue starvation problem there is a filter screen at the bottom of the Fuel Tank and 2 Fuel Filters that can get plugged up.
Also if your hand primer has a shiny Aluminum body on it; it is the old style and they are noted for allowing air to leak into the fuel system when they get old.