Add the salt pork and 1 cup water into pot. Simmer for about 10 minutes Add large onion chopped to the pot, let simmer for about 20 minutes until the onions are translucent. The longer you let simmer the more flavor blends. At this point add the potatoes and clam juice to the pot. The clam juice should cover the potatoes.
Cover the pot and let simmer until the potatoes become tender not mushy. Then add the clams, butter, dash of salt and fresh ground pepper. Cover pot and let simmer for 5 minutes, then turn stove off and let set the chowder sit on the stove.
At this point if I'm making it a day ahead which I usually do because the flavors seem to blend better, this would be the stock. Pack it in ice to chill quickly then refrigerate.
If serving the same day, add the cream and whisk in the flour to the desired thickness. Serve with fresh ground pepper and chowder crackers.