Okay, some really good advice here. So, to start diagnosis, or maybe even help come up with some ideas...here goes.
It is a carb engine. That is the reason for the 180 therm. Plus, the engine is newly rebuilt, and a brand new engine tends to run warmer, so I wanted to make darn sure that the therm opens up soon enough.
I have burped and filled every possible air pocket in the system, so I am positive there is no air in the system, so that can't be it either. Flow of coolant is superb, no cavitating, and the hoses have a great "feel" to them while running. Now, I have made no changes at all yet...but I drove it last night, the thing came up to 180...after running for 15 minutes, and then today I drove it again, and it never made it above 110! It's killing me. Every logical troubleshoot I have is being laughed at me by this engine. Ive built many engines, and had great sucess. I've once or twice had to change cooling systems because they were getting too hot, but I have never had one unable to warm up! Shoot, I've got a half a dozen aircraft engines under my belt as well...and I'm the once who test flew them too...I have plenty of faith in my skills, but this one has got me totally stumped!