Bring a large pot of salted water to a boil
Combine the chorizo and oil in a small saucepan. Cook over medium heat until the chorizo is crisp and the oil is deep red, about 8 minutes.
Arrange the clams in a single layer in a large, deep skillet. Pour the beer over them. Cover and steam until the shells open, about 5 minutes. Add the open clams to the chorizo oil (discard any unopened clams.)
Add the spaghetti to the pot of boiling water and cook to al dente. Drain, reserving 1/4 cup of cooking liquid.
Stir the reserved cooking liquid into the clams and sprinkle with chopped parsley. Serve over the spaghetti.