Spark Plug Gap?

[Jordan]

I have searched the site on spark plug gap and the concensus seems to vary from 0.7mm (0.028in) to 0.035in.  I was unable to find anything in the BBB, although my eyes were glazing over by the time I reached the end of the book.  Both the Veloce and Haynes workshop manuals for the 230SL list a 0.5mm (0.020in) spark plug gap.    I have not seen anything this low specified on this site.  I am going to install Bosch VR9DC+ plugs and I have a 051 distributor in a late model 230SL.  What is the correct spark plug gap.  The new plugs currently have a 0.028in gap.  Many thanks.

[mdsalemi]

Jordan, .031 sounds about right--between the .028 and .035 for stock setup.  Never heard of .020 sounds a bit tight to me.  I'll have to check my own Haynes on that one!

If you have an electronic ignition and higher voltage coil, you can open up the gap a bit since the spark is larger.  I'm running about .035+ on NGK BP6ES with Pertronix--but I have their Ignitor II high voltage coil.

[badali]

I have been setting mine at .035.  I also just bought some original Bosch W7DC plugs for the next time I change them.

[W113SL]

Brad:  Good move, the original W7Dc are hard to find.  In my experience , the engines especially the earlier non transistorized ignition ones, run better with these original copper core plugs.  I've tried the WR7 and WR9's but when the engine is tuned correctly, i.e. not too rich at idle, the W7's are best in my view.

Pete Lesler
1967 250SL
largely original