I run my engine pretty hard for hours at a time to travel between cities, its just "pretty warm" at the end of all that, I can put my hand on it for 15 secs or so before i feel pain. Or I just have a high tolerance for pain, lol.
I've never spat on mine, but the advice in one of the previous pasts that says "if you can feel the heat from 5 inches away" makes sense, since my engine runs fine and I can only feel the heat from 1-2 inches away, nomatter the weather.