"Turning the delivery valves" has been proposed as a way to increase fuel to the engine and it goes like this-
1)Loosen injector lines at the IP. 2) Loosen the two 13 mm nuts above and below the 15mm "housing" on the IP. 3) tighten the 15mm "housing". 4) Lower idle as it will increase.
This has been done on many other Bosch IP's according to some people with great success. Several others have said this is not recommended as you may throw your engine's timing out of whack. I'd like to hear from those that have done this on a 617 and the results/problems/issues, and others who think this is a bad idea and why. You can see threads at schuman and superturbodiesel on this idea.