The shop manual I have for my 603 doesn't mention the drip method so I don't know how to advise you.

The shop manual for the 617 says:

- turn engine so it's just before the start of delivery position for cylinder #1

- remove the delivery valve and spring for cylinder #1, refit delivery valve cover and fit drip tube

- loosen the return fitting on the fuel filter, hand pump until fuel is expelled from the drip tube

- set the throttle linkage to full load

- turn crankshaft in direction of normal rotation until you see one drop per second from the drip tube

- adjust the IP if necessary so the point of one drip per second coincides with the start of delivery spec

Things you'll need figure out for your engine:

- what's the start of delivery spec? It's not 14-15 ATDC. That's the spec for the reference lug in the IP. It should be something like 20-30 BTDC.

- how do you pressurize the system? Maybe get an old carburettor type fuel pump and fit it between the fuel pump and the main fuel filter. Pump by hand to build pressure.

- does the procedure for the 617 apply to the 602?

BTW, that is the delivery valve you have circled in red in your first photo.

I recommend you search the archives for setting IP timing for the 603. Much easier and cleaner to do it using the reference lug. Again, with apologies to the techs and purists because this is not the way MB inteneded IP timing to be set.

Sixto
91 300SE
87 300SDL
83 300SD