Mike:
You must match the plugs and wire set -- if the original plugs were
non-resistor (as I believe they are), you need to get solid wire,
non-resistor wires OR change the ends to non-resistor ends. All
platinum plugs are resistor plugs, and at idle you have too much
resistance in the secondary circuit for good ignition. Not a problem
at higher speed, just at the low end.
Timing is 0 degrees because you likely have a vacuum retard system
active at idle -- as the engine speeds up, the timing is "unretarted"
and the mechanical advance takes over. Get the wires and plugs matched
up and see if that doesn't cure the idle roughness -- it's VERY common
on Benz automobiles with platinum plugs installed with factory wires.
Don't change the timing, you risk detonation. Also, check the mixture
with a CO meter -- you are probably a bit lean. Make sure the intake
manifold does not have any vac leaks (you can check with an unlit
propane torch -- direct a gentle stream of propane along all the joints
with the engine idling -- if the idle speed changes, you have a vac
leak). You also need to check the valve tappet clearance, you do NOT
have hydraulic lifters on that engine. You aren't hearing valves
ticking, you are hearing spark knock, most likely!
The rubbing sensation is probably worn out rotors. Rotors need to be
changed about every third pad change on these cars -- if you can feel a
distinct lip on the rotor at the outer edge, replace them (and get new
pads, too) -- they are inexpensive ($60 per last time I bought some)
and only a major PITA to replace (remove hub, unbolt from the rear --
10mm socket-head bolts), bolt new ones on, repack wheel bearings,
re-install caliper.
Peter
