I have a 68 289. Ever since I got the car Ive had overheating problems. I recently installed a 4 row radiator that keeps it cool at half temperature. I only drive to and from work and it remains cool. This weekend I took a 3hr drive to visit the parents back home and I encountered an hours worth of traffic and my engine soared to over 4/5 of the temp gage. Its a stock gauge so I dont really know the exact temperatures it is reaching. I have a Gano Filter on my top radiator hose and the radiator is new so its not clogged, I flushed my system out a couple weeks ago, and I am not running a thermostat figuring the engine is always getting a supply of cool water. Everytime I clean out the filter there is large particles of what looks like brownish reddish rocks. Anything you guys recommend would be appreciated, perhaps I should put in the thermostat again.