No fan shroud causes how much fluctuation in temp?

[nomad]

I had the fan shroud off and took the car for a longer drive today. Temp was 92*-95* and I romped on it a couple times to see how it did.

Temp needle stayed hovering in the middle of the section to the left of the center mark (like 11 o'clock) and I take this to be normal with a regular 88* thermostat.

Once I go into traffic on surface streets it started creeping up to just shy of the center line. I figured this was due to the shroud not being there and in the beginning it would drop when i got going. It started staying up, "touching" the center line so i cranked on the heat and it helped. I was not happy when I smelled coolant when cranking on the heat though.

Everything seemed to stay pretty good once I got it on the highway but cruising along at 80mph the gauge stayed about a needle width away from the center line, so it was higher than what I might call "normal".

Whatcha think?

I may get a 75* thermostat and replace the water pump (which is new but might be "weeping"). I've already replaced all that and all the hoses when I did the head.
 
Guess I'm just paranoid. I'll put the shroud back on and see if it makes a difference. I'll also be doing another oil change (to check for any coolant leak)  and a flush/fill of the cooling system.

What should I do to check the heater core? I'd hat to have something like that give me trouble after all this.

[tjts1]

Having the shroud in place will improve the efficiency of the fan dramatically but the temp variations you decribe are very small. My temp gauge varies from 2mm below the half way mark to 2mm above and I consider that normal still. My electric fan kicks in at the upper end of that range.

[nomad]

Interesting, I'm super paranoid of overheating this again and having another cracked head!