Temps at the radiator cap and temps at the #4 piston are two different things since the front cools more than the front due to the coolant routing. Taking the temp at the radiator won't tell you much.

Check that you didn't have an air bubble in the system. If you let it idle w/ the cap off and the fluid level doesn't change much, you've got it full. If the fluid level rises as the temp increases this indicates there is an air bubble somewhere (air expands a lot as it heats, water not so much).

A quick check of the radiator is to pull it and put your hand over the bottom outlet and fill it w/ a hose. When its full, pull you hand off the bottom. If it doesn't gush out the radiator is not flowing right. Not very scientific but its a start.