What temp should a 302 run at? Relay switch?

My relay went out on my Fan. I was shopping for one, and saw they make ones from 165 to 220 degrees to come on. I was wondering what one to get.
Any certain brands you guys like?

302
Aluminum, Heads, intake, and rad. Holly 4bl.
Mostly road driving, might see a trail here and there.
Thanks Guys

i dont have a electric fan, but i have a 302.
my engine runs about 190 operating temp and the thermostat opens at 230 - according to my temp guage any how. I hope that heps you.

are you talking electrically, or the thermostat for the coolant? I think most carbed engines have a 180* thermostat, while fuel injected are around 190. I run a 180* in my carbed 302, and it's good.. gets warmer when idling and no airflow, but nothing over 200*..... hope it helps...

The optimal cylinder head temperature for water cooled gasoline engines is 200F. The thermostat should open at some point before that. The fan should com on at a point that will allow cooling at low speeds when there is no air moving through the radiator. I would say 180 or less.
Modern emission engines run hotter than 180 thermostats to keep the head temps up where they will run lean. If you have a performance engine or care more about HP and mileage than emissions and you need to know for sure then buy and mount a pyrometer on both heads. Adjust the thermostat to get your desired head temp.

Hey thanks for all the help. Looks like 180 is the one for me. Well until i do my EFI swap, then i get to switch to a 190. Got to love the old money pit.;D
Thanks to all.