jeff5347 said:
Just to add to what Jim as provided... Typically these engines don't make as much power until the 180-200 deg range. Don't confuse the fact that guys with modern computer controled lt-1's and ls-1's etc install 160 stats as a power adder. What it does in the computer controled engine is trick the computer into giving up some extra timing and that's where they get the power. You need the stat and a re-program for it to work.
If you run a 160 stat in our cars the stat will open, the system will flow, and the temp will come up to what ever the cooling system and running engine balance out to. That's typically more than 160 and the stat will never close again. Say you have a good cooling system and it balances at 170 degs. Your engine will never get to 180 and you have a slight loss of power and the engine may never quite that wot sputter like a cold engine.
Switch to a 180 stat and now no fluid flows until the stat opens, the engine is properly warm and as the system starts to cool things down to 170. The stat closed when the temp goes below 180 and the cycle starts all over. You have a system that can maintain 170 without a stat but with teh stat your temps are much more consistant. There is nothing like looking down and seeing that needle on the magic number of 180 all day.
All this is very basic, more HP makes more heat, different water pumps, core sizes and type of fan all come to play so if things don't dial in on my numbers look at your system components.
My iron headed stroker with a brass modine core, stock pump and aftermarket (low dollar from summit) five blade and clutch runs just at 180 until the weather gets into the 90's and then climbs up to no more than 190 under any condition. The alum headed 350 with a stock AC core stock pump and stock fan runs 180 no matter what or where so far and I've had it out in over 100 deg temps.
You can hop into the 'heating cooling' section and use the 'search' to read other viewpoints that mostly agree on this. 
