Making grape jam

I came home the other day to find a glad-ware container of concord grapes on my front porch.  I have two friends that have grape plants and both of them had one of my glad-ware containers, so I wasn't sure who had given me these beauties.  Turns out it was my next door neighbor, she's been planting all sorts of fruits & veggies (recently put a few blueberry bushes in her yard too).
Have you ever had a whiff of concord grapes?  They truly smell like grape candy, the aroma was so strong that my entire kitchen smelled like Welch's grape juice (which was wonderful).  My husband suggested that I try to make a spread with them, but after friends stopped by and snacked on them, there were just a few left.  So I tried the local vegetable market, Farmer Q's and they had quarts of concord grapes - I was on a mission!
Google being my research tool of choice, I came home and promptly googled how to make grape jam and came across this recipe (click on post title).  I didn't know the weight of my grapes, so like everything else I cook, I just eyeballed the quantity of sugar and lemon juice.  Other than that, I followed the recipe to a "T".  The finished product is a little looser than true jam, but was a delightful treat on our pancakes this morning!  Thanks neighbor!