I'm saying that 300 is right on the line of acceptability. I've run many engines WAY over 300
for a short time and they did fine afterwards, but you really don't wanna run your engines like I run my engines
I seem to have the midas touch when it comes to luck with engines, and if your engine goes OVER 300 you should shut it down and let it cool off, and richen 'er up, then run it again.
chances are if it WON'T stay under 300, it's probably just worn out, or you have an air leak in the engine, OR you live in Arizona, LOL.