The time limit to edit is little over 24 hours. It's in place for a variety of reasons but the biggest two are
- Spammers will plant posts so they go under the radar and edit links in later.
- It's rare but people have removed their origianl post, it destroys the thread and the contributions of others members.
Generally we don't take requests for edits after the time has expired but will make exceptions such as if you have accidentally disclosed something you shouldn't have.
I will remove dead links too, send me a PM.