Yes I agree, it's important to test for both idle and moving, but I couldn’t take it for a drive, the seat belts aren’t all in and I was watching the kids, so I couldn’t go anywhere. None the less, I had the same problem while test driving the car previously, so driving or idling, it reaches too high of a temp.

I could sit idling on the Los Angeles freeway for longer than 20 minutes; all you need is one accident ahead of you at rush hour. I've experienced it plenty of times. So I need the car to be able to withstand 90 degree ambient temperature and at least 20 minutes of idling.

I had a 76 firebird with a 400 and it never hit these kinds of temperatures. Yes, the 455 is hotter, but again, the 455 cars worked fine from the factory in California, just like the 68 400s with air conditioning worked fine in California when they were new.

I think I just need to look at each part of the cooling and timing systems and make sure their dialed in. I want to keep it under 200 degrees at all times. At the most, it should never reach the boiling point of 224 degrees. I think that's possible if everything is set properly.