"over heating" is kinda relative . . . . when the FIRST "Pacific Nationals" (mopars at the strip now) were held in Vegas, in AUGUST, it was HOTTTT outside for sure, think like 110 F in the shade !!! . . . anyhow, I drove my 300Hurst with the AC thumping out cold air, at speed on the highway - was running 205-210 F getting up to 240F at the top of hills, but cooling back down to the 205-210 . . . was not pushing anything out of the rad . . . was factory rad/shroud/t-stat and I had put mechanical temp gauge on the car. Sure it was hot, but no pinging or adverse effects to the old 440 - and NO WAY I was going to NOT use the AC !! . . . .and today - the cars are running at the 205-210 F temps as "normal" . . .