Ok - so, we overdid it a little:
Great-great-grape jelly:
Friday p.m. 1 pail and a half of Concord grapes.
Saturday p.m.: , mash/boil/squeeze/strain = create juice stock (27 cups juice =~2 gallons), and 3 quarts of secondary juice (squeezed from mash)
Sunday afternoon: 27 cups juice - 8 boxes pectin, and 40 cups sugar = 12 - 16 ounce jars jelly 6 - 10 ounce jars jelly and 18 - 8 ounce jars of jelly OR about 296 ounces of jelly or ~ 2.3 gallons of jelly.