[TR] Uncool Coolant Confusion

[terryrs at comcast.net]

I confess, I'm not getting the nuance here.
I rebuilt the engine on my TR3A 10 years ago and it always ran cool using the yellow multi-bladed upgrade fan and stock radiator.  
I've rebuilt it again using new rings but the same Mahle pistons and same honed liners.  Did put in a new radiator from either Moss or TRF.  Runs spectacular with so far about 5,000 miles on it.
But...
On mild days the engine touches 190 to 200 instead of 160-180 it runs on cool days.  
Block was boiled and cleaned.  New radiator.  Proven pistons and liners.  Only change I made was to bring the crankshaft thrust bearings within tolerances by going oversize.  
I'll break down and install an electric fan if this doesn't clear up this summer.  
Thoughts?

Terry Smith, '59 TR3A  TS 58667
New Hampshire