I have notice this trend over and over again.
I go to a car show early in the day, nice and bright out and if the show is even 1 hour away I don't need to usually turn a fan on.
I run 2 16 inch electric fans, manual switches, no thermostat and the temp usually settles to about 180-185 on the open road.
I go to the show without touching the fans.
On the return home it is dark or getting dark, the air is deffinitely cooler , the lights are on and I suddenly find I need 1 fan on all the time or the temp climbs to 200 where I will not let it get any hotter.
I need ONE fan on all the time and 2 if the traffic slows down.
I really tested this again last night and I definitely feel our cars benefit from having the lights DOWN.
It must aid air flow through the rad, could also just be my car but when you can really control temperature you can notice trends.
I know most of you just drive and have to accept whatever temp you arrive at but most of the time I control the temp between 170 and 200 by which fans and how many I turn on.
If I am just cruising I will let it creep to 194 where it seems to stabalize but if I aticipate a little more spirited driving I will quickly cool the motor and oil OIL down to the 170-175 range.
Also just before getting home I will turn all fans on bringing the temp down to this 170 range and I can do it within a mile or 2 at most regardless of what the motor is running.
I find for cruising milding I prefer the 190 but now when I want to lean on the blower I like it in the 170 range to prevent any chance of detonation.
Yes to me head lights UP or DOWN definitely affect temperature and Down had proven to me to improve rad cooling.

 

I find that kinda the reverse ferom what I'd expect....
lights down blocks airflow eh?
Some years ago I put in a set of
Eckler sugar scoops with square lights, now they are modernized, but the back sides allow for even more airflow as the lights are further forward, leaving the large shell/scoop holes in back unblocked...

 

Do you have the flaps in place meant to protect the lights?

is so pull em off this will help some

 

Yes my guards are in place.

No I don't need help. My cooling system is great. I don't have a heating issue, far from it. I am just noticing a trend and commenting on it.
I don't need to do anything.

 

Yes Gene this seems to be in reverse of what you would expect.
But like I have said over and over again. " Ask the car"
If you ask the car what it likes often it will tell you. Try different things and get a feeling from the car what it wants, Sometimes asking on the forum is the wrong aproach.
Try the modification and see how it works for yourself.
My car likes it lights down to stay cool.

 

....when headlights are in up(on) postion, it seems possible they are interfering with air flow thru grilles...in otherwords,creating turbulance...
(Just stick your hand out the window at 60-70 flat against the wind)...

Rich

 

I always ran with my headlight bezels removed. This acted more like a
scoop to send air to the front of the radiator. With bezels in place, this
effect would be eliminated. Thanks for the observations, Norval.
Do you have the chin spoiler in place ?

 

I think the heat from the headlight bulbs warms the air that flows through the rad.

 

Yes Sir I tried running without that little 2 1/2 inch spoiler and I also noticed a trend to run hotter.