No, the OM602/603 engine manuals also specify a dial indicator method. However the cam tower marks are fine for a ballpark measurement. You need to do it about 4-5 times and average the results. I did it both ways - dial gauge and cam marks - and the numbers were within 0.5 degrees (my chain is stretched 4 degrees, have new chain, waiting for crimp tool to arrive!). I'd say that if the cam is worn, it should be replaced - not adjusted for - as the valve lift will be too low. So far I've never heard of an OM60x camshaft wearing the lobes, they are built pretty beefy!
