Scrub clam shells well to remove all sand. Lay in the bottom of a large kettle and cover with the boiling water. Cover the kettle and let steam about 15 minutes. Open the clams, saving all the liquor. Chop clams. Fry the pork about 5 minutes. Add the potatoes, onions and clam liquor, and cook about 15 minutes. Then add the clams and boil for 20 minutes. Melt the butter, add the flour and blend, stir in the milk and cook about 10 minutes. Add seasonings. Combine both mixtures and serve at once.