Hello,
Being relatively new to W116 ownership, I am at the stage where I have worked though most obvious servicing tasks and now would like some advise on fine tuning the old girl. I have a timing light, some pages of the workshop manual and most of the useful tools but I don't know the best practice for servicing the ignition and fuel injection system or even if there are hidden filters inside the unit. Is it worth servicing and cleaning injectors as well or is leaving it alone best, if it's running well? My car is a K Jet model from 1978 six cylinder. Thanks in advance.
BCDC
Things that come to mind on the M110 would be valve lash adjustment. Other K-Jet specific items would be the filter at the main supply line to the distributor (A0000746086), injectors and injector seals. Injectors are relatively cheap (especially compared to D-Jet), and I'd just replace the lot if the car is stil on its original set.
Ignition leads, spark plugs, maybe coil as well. But neither is a must if the car runs well.
And then a mixture + CO adjustment to spec.
It is amazing how well these cars run when they are dialed in. The key for me was the fuel system. With the advice of others here, I checked the system/control fuel pressure to ensure the wur and fuel distribtutor are working properly. Change the fuel injectors out also made the most immediate difference.
Getting my right ended up including finding all the vacuum leaks, changing the intake manifold gasket, which lead to replacing hoses, temp switches, etc. There were a number of things that previous owner had not done properly which got fixed back to original. my car is great now. Good luck with yours!