I hate to say Ive never adjusted this motor for valve lash ,having the service done this sunday and will report back on lash before and after to see how far mine were out of specs.It seems on this daily 83 300cd I complete a DIY service of some sort once a week .Next week who knows ,this car is like owning a service fleet in one vehicle. Sooner than later it will also get some preset tested injectors ,all this to bring back the peepy motor I remember it being when I bought it 6 yrs ago.Ive never ran the compression #s on this 617 so it will be getting a heart checkup for sure.