Keepers of Time
The Keepers of Time faction was one of the instance factions added in The Burning Crusade. There is only one way to raise your Keepers of Time faction, by running instances. Black Morass and Old Hillsbrad will give you reputation towards your Keepers of Time faction. Out of these two instances Old Hillsbrad is the best one for you to farm. At level 80 you'll be able to clear all of trash mobs in this instance without much trouble.
If you have some decent gear and know what you're doing you will be able to clear a lot of the trash in Old Hillsbrad on Heroic difficulty as well. The Quartermaster for The Keepers of Time is inside Caverns of Time itself.
Farming Keepers of Time Reputation
As said earlier the best place to farm your reputation with Keepers of Time is Old Hillsbrad. You will be getting 8 Reputation per kill. Not everything in the instance will give reputation and not everything is worth even killing for reputation. So in order to help you out I've compiled a quick video of the path I use to farm reputation here.