... I can seriously say with some authority that the 560SEC EHA valve is "one piece of craftsmanship" ...
How refreshing to read something like this, Cherry2728 (and Tyrone D.) ...
… IMO, the whole KE-Jetronic is a remarkable piece of mechanical engineering … and the decision for that system is one of the most typical representatives of the spirit 1980‘s MB‘s were designed with.
... in order to tune the EHA without having to take it off the CIS head, I made this adapter below that works perfectly for tuning the 1.5mm Allen setscrew ...
From the pictures it seems that the adapter redirects the fuel flow 6 times by 90° per line (inlet and outlet). … If so, these 12 redirections may cause a pressure loss, that leads to a setting of the adjustment screw that‘s too far CCW when the EHA is mounted back directly to the FD.
With a design according to the attached sketch fuel flow redirections per line are reduced to 2 negligible soft (~45°) bends … of which the one on the right isn‘t necessary either. …
The actual purpose for this adjustment screw is the new
EHA‘s factory calibration. Changing it is an option that should only be considered in case of a problem inside the FD (Fuel Distributor), if replacing or refurbishing the FD does not come into consideration. … Also a refurbished FD might require EHA tuning, for instance, if its diaphragm or its springs differ from original parts.
And in case of a problem with the EHA itself (besides removable contamination) I suggest to replace it.
Before the EHA adjustment screw is touched, I suggest to make sure that everything else is in order, including the ignition system. Also things that are often overlooked, like e.g. the air flow meter plate‘s “zero position“ and it‘s play, should be in order. … The EHA tuning should be done according to EHA current and lower chamber fuel pressure