maximum engine temp

freshayr said
What's the maximum temp you should let your engine run? I have a 160 thermostat in it but on these really hot days it's getting to 200-210.

I'd say 200-210 is still normal when it's really hot outside.

freshayr said
Also, my engine seems to run hotter going down the road at 70 mph that it does at lower speeds or even idle. I would think I have max air flow at highway speed to help cool it.

Do you have pull or push fan? A fan in front of the radiator (push) restricts the air flow and could cause that.