74 Spider running hot

["Mark Kunkel" <mkunkel@domain.elided>]

Hi, folks.

Data, for the collective and considerable wisdom:

74 Spider with Crane electronic ignition, coil, and optical-trigger Marelli
distributor
Thermostatically (radiator surface-mounted bulb) switched pusher fan (i.e.,
in front of radiator) installed
  last winter after self-destruct of yellowed fan blades
160 degree thermostat and full and fresh and proper mix coolant
3/02 tune-up by nearby Alfa shop to the tune of $800 (ouch) with adjustment
of valves, Spica, etc.
  (I didn't want to replace the filters myself...lesson learned...and didn't
want to mess with
   the Spica...ditto...car was running cool but rough to start and poor
mileage)

Now the car gets much better mileage than before the tune-up (23-25mpg in
vigorous mixed driving), starts easily, good and smooth acceleration curves,
but:
  * some valve clatter when pulling hard, not varying with different brands
of gas
  * hot running...the needle (accurate, or at least reliable....) pushes 210
whenever I stop at a traffic
    light, worse with hot weather, and whether the fan is on or not, and
even on the highway it's at 180
  * rough idle
I _love_ the fan idea (much quieter non-Italian engine noises and yes,
additional power), but don't want to warp those beautiful heads if I can
help it.

Pulled the plugs (Autolites) this AM, and they are chalky white.

Replaced them with the Platinum +4s I had bought and not used when I did the
Crane stuff, and the car seems to idle better, but haven't tested heating
yet.

Suggestions?
  Timing (will check tomorrow)?
  Mixture (still afraid of the Spica, but I'm going to get over it)?
  Thermostat/fan/fan thermostat?
  Plugs?
  Something else?

Many TIA for any help/insights.

Mark
Carrollton, GA
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