ASAP! timing?

my caprice has been running hot lately. like 230-240. I was coming home friday and the needle was off the chart, so i stopped and waited for it to cool. then I took it home, and it took way to long to even make it to 40mph, and wouldnt go over, and got way too hot way too fast. Could it be the timing chain? and if so, how much about would it run me to get that fixed?

Unlikely.

Is it overheating when moving or will it over heat at idle as well?

How is the economy? Sounds like a classic case of a plugged catalytic converter.

It just overheats when its running, but idling does get pretty hot. When its hot and driving, it knocks at around 35 too. I'm pretty sure thats a lifter hitting the valve cover. The economy is fine, and I'm pretty sure the cats ok. But supposing it isnt, would it cause all that that quick?

A plugged cat would cause quite a bit of overheating like that.

I assume you have checked the coolant level. Is the upper hose hot when this happens. Could be a stuck thermostat as well. If it is only overheating when driving, then look at a collapsing lower radiator hose.

thermostat had crossed my mind. I'll probably try that first and hope its that simple. Coolant levels are fine, and upper hose is hot.

Mine was a stuck t-stat.

sounds like a stuck thermostat to me, too. If it won't do over 40, though, even floored, then I'd say your cat is plugged.....happened to me so bad once the car wouldn't do 10...car got REALLY hot, too...wish I'd known more about them back then.