The engine you have is a Tecumseh LEV- 120. The spec. number is XXXXX
Please see this page for details. It is the Tecumseh manual and will give you the steps involved in putting it back together. http://www.smallenginesuppliers.com/html/engine-specs/tecumseh/Tecumseh_quick_reference.pdf. Let me know if you need anything else. The information you want starts at page 18. Just look at the pictures and you will find the one that looks like yours.