Thats alot of OC on a clawhammer. I have that same processor too. Mine was stable at 2.77ghz, at 2.8ghz everything turned sour. Never tryed to stablize it or anything. By that time my AV8 temp sensor was giving me false readings.
But 247mhz seems a little low. At 234mhz my 4000 hit 2.8ghz. But im not calling you a lair.