Would like to check and setup the timing for my 1986 300E with M103 engine -- How is this done on this engine -- can the distributor be turned to adjust timing ? For my Saab I just disconect the vac line, loosen the distributor and turn to desired setting. ( using my timing light ofcourse)

the timing can be checked by conventional means using a stobe type timing lamp, it however cannot be adjusted, if the timing is not correct there may be two causes, either 1 the vacuum supplyto the EZL control module is disrupted vacuum hose off, loose etc, or the EZL it's self is defective sending the wrong timing setting. those are the only two way i know of the timing being incorrect,there may be others that i am not aware of.