1987 420SEL timing - HELP!
 

Hi everyone, New to the site - and loving it! I just checked the timing on my 420sel and with the vacuum disconnected from the ignition module, it's reading almost 16 degrees.....question: Is there a manual / mechanical way to retard the timing back to 12 degrees? Obviously turning the distributor in these only changes the advance feature. I have drilled a small hole in the distributor cap on No. 1 cylinder - marked a line on the center of the rotor - and with timing light, have phased the rotor inline with the No.1 terminal / wire. Could I be at 16 degress because of timing chain stretch? Any help would be appreciated - this is all pretty new to me - Thank you !:o

Leave the vacuum like connected. The distributor is staticly aligned with the cams and the crankshaft damper. The EZL controller performs all advance/retard function via an internal program.

420 sel timing issue
 

Great.....and thanks...( more confusion ).....with the vacuum connected the actual timing reads over 20 degrees. The service tag calls for 12 degrees..question: when / how do I find the 12 degrees? I have a small stumble when I stab the throttle - to the point where it feels as though I have to "backpeddle" a little in order for it to go. It won't even spin the tires a little bit in a gravel driveway - but has great acceleration and tonnes of power on the highway.........the lag off the line is killing me. Your response(s) are GREATLY apppreciated!!:)

As stated the timing is created electronically from inputs including the engine position input from the crank sensor. It is pretty cool how MB places an advance mechanism in the distributor so that the rotor and cap are somewhat aligned when the firing event occurs. Mind you though that the event WILL occur whetehr the advance has moved the rotor or not.

Many other engines accomplish this matchup by having huge contacts surfaces at the end of the rotor such that they are opposite the cap contact for significant turning arcs.

There is a trimming resister on many models that can be removed or altered to change the created timing amount.