If the engine is rebuilt it will run a little hotter because of friction. I was just "burping" my cooling system yesterday. I was amazed at how much air was stuck in the system. You really need to be running a shroud to help direct airflow through the radiator and not around it. On my A/C car there is one seal missing at the bottom lower left of the radiator support (front of car). All the hot air from the engine bay blows out through this opening because it's the path of least resistance. The same will happen if you don't run a shroud. All the air will flow around the radiator instead of through it. I need to fix this because the hot air will only get recirculated through the radiator again. Congratulations on firing up the new engine.
