I have a general question regarding this engine in my 1996 SL 500. I am aware that this particular engine has 4 valves per cylinder. I believe it was used in 96-98 SL 500's and is designated M119 and used in other earlier and later V 8 models. I have read that the engine has 16 spark plugs but I had them replaced at a reputable shop and they used 8, not 16 plugs. Can anyone tell me which V 8 engines from Mercedes use 8 spark plugs in this era? Mine runs perfect and I heard that the later engine 3 valve engine had a little less power and better economy. I have no thoughts of switching engines.

 

Your motor in the R129 (SL platform) use 8 plugs. Take a look at the link below, the Wiki page for this platform surprisingly has some good info. Hope this helps you a bit.

https://en.wikipedia.org/wiki/Merced...996–1997