Cook bacon in large pot until crisp. Remove and drain and crumble. Cook onion and celery in bacon fat until transparent.
Stir in flour and cornstarch, salt and pepper. Add 3 1/2 cups clam juice and cook over medium heat until bubbly, add milk, clams, potatoes, carrots, celery, and onion, & bacon. Cook stirring occasionally until all vegetables are cooked through. Add cheddar cheese stirring to combine and serve.