I'm reaching the endpoint on the refurbishing of this old 1969 280SEL so when I noticed that it seemed to lag a little at low RPM I decided to check the plugs and then advance the timing a bit. All the plugs checked out except #4 which was a little wet. I then advanced the timing 4 degrees or so and test drove it. The difference was amazing. Lots of pep and good acceleration. I think I'll get a hotter plug for cylinder #4 just so it stays clean. What would be a good Bosch replacement for the W7 DC that I'm using right now? Any ideas out there? Thanks all.
Thom

Thom,

On my 190SL I went to a NGK BP5 from a BP6. I believe that the BP6 is the equivalent of the Bosch you are using. Be aware, however, that a hotter plug may result in early detonation (a bad thing). However, you may have a different problem. I'd be concerned that #4 isn't firing all the time. Might want to check out your ignition, and look at putting in an electronic ignition.

__________________
Bill Streep
San Antonio
'57 190SL (toy)
'08 S5500 (mine)
'09 CLK550 (wife's)
'06 SLK350 (daughter's)
'11 GLK350 (daughter's)
'03 CLK310 (spare)

Thanks. Just as you were responding to this question I submitted a new thread. I'd like to see what the others might think about this. Cylinder #4 is definitely working so I don't want to do anything rash here. Ahhh, perhaps it just needs a valve adjustment.
Thom