How do you replace timing belt 1984 corolla?

First get a Manual
Second read it.
There are to many step in the process of changing The Timing Chain to go into great detail. [http://www.themotorbookstore.com/toycor19.html Go Here for a Manual] Good Luck and Remember.
Change Your Mind, Not Your Oil.
Use the First In Synthetic Motor Oil's.
See My Bio For more information.