What's the proper gap for spark plugs on a 1985 1.9L wasserboxer?  I
can't find it in my Bentley manual anywhere.

(The inspection of the spark plugs shows they're currently operating
at a gap of approximately 2mm, though I don't have a gapper handy for
specifics.  My engine is running rich, which is leading me to evaluate
the ignition system for problems such as possibly a weak coil or a bad
HCU/hall sender.)

-Kyle