[BOBOCobra]

I have done all of this. Different stats, no stat, OD pulley....I have done it all. Here is your first clue. The Rad is 30 degrees cooler than the engine using your infrared. This eliminated bad senders, etc.. Why is it cooler? You are not moving enough water. Why? you may have to overdrive the WP so it cools at idle (you have that), you have an air pocket or you have a partially plugged Rad or collapsed hose. What else can it be. The T-stat discussion is nice but it is not the reason for a 30 degree difference. Start easy, check hoses, get ALL the air out and if it continues you may need to pull the rad and flush it. Someone may have shoved sealant in the block after the build and you pushed it all into the Rad if you did not do a long and proper block flush before first fire. Regarding the T-stat I found my best was 180. 160 is too cold if the system works properly. 190 was a little on the high side for me. Once you get the water flow correct you can play with the T-stats. Until then you need to flow more water from the Rad to the block. My guess is air. You need a t-stat, it allows the water to flow properly in a street car and keeps consistent temps. Wha are your temps at ram air on the highway?