Strange coolant problem
Just finished a cam/vlavespring swap, got about 200miles on the car. Filled radiator with 50/50 Dexcool and water. Car will idle all day around 200, and usually will cruise between 200-210. First time headed to the track(20miles), I noticed it was creeping up to around 220-225, and when I got parked, it had blown it out the overflow. So I assumed air..jacked the car up, let it run with cap off, and could see good circulation,etc..Thought all was well, and drove back home, plus about 50 more miles with no problems. Well last night headed home from the track it runs up to about 220ish and I notice it seems to only do it when around 60mph and 6th gear,so low rpm's. Seems like higher RPM's possibly help. Got home, and it hadn't blown any out of the overflow this time??? I know the fans are working bc they ran for a few seconds after turning key off. Thinking possibly still trapped air? Maybe a new cap and thermostat?? What baffles me is it runs perfect at idle, and never gets past 220 or so, then returns gradually to 200-210. Any help or ideas are appreciated!!