OVER HEATING WITH A 318 ?

I have had issues with coolant overflowing after a coolant change, trapped air I suspect., After a few heat cool cycles it leveled out and went away.

I don't run an overflow, with the level properly set in the engine / rad it will never overflow unless it overheats, which it never does, 100 deg days, idle all day long, stock 273, 7 blade fan, no shroud, 2+ inches space between fan and rad.