In a large pot over medium high heat, combine 8 quarts of water,salt and garlic.
In a large sauté pan over medium high heat, heat 4 tablespoons olive oil until hot, add onions and sauté until just soften,add garlic sauté about 30 seconds. Add clams and red pepper flakes and saute 1 minute. Add wine and clam broth cook uncovered, just until clams open, 4-5 minutes.
Add linguine to boiling water and cook al dente according to package directions.
Reserve 1/2 cup of cooking water, then drain linguine and add to pan. Cook over high heat, tossing occasionally, until linguine is just tender, about 1 minute. Add some reserved cooking water to keep moist. Remove from heat. Add parsley and butter, tossing to coat.