PJ,
At last weekend cookoff in Mt Vernon, I cooked my spares for 6 hours, including one and one half hour in foil. Unlike Stogie, whose cooking skills I greatly respect, I find cooking longer in foil ends up with meat separating from the bone on the underside of the rib. Unfortunately, these spares were still not tender. I made the mistake of buying the meatiest ribs I could find at Peoria Packing. They probably weighed around 3 lbs each slab, even after trimming to a St. Louis cut.
I also think my mistake was judging doneness merely by how much the meat had shrunk from the bones. Because of the thickness of the meat, what normally appears as being done was not. I should have tested the tenderness of the meat with the toothpick. Live and learn.
As for brisket, my 12 lb packer cut brisket took all of 19 hours to get to 185 degrees--not quite where I wanted it but was running out of time. Another hour or two would have been perfect. Normally I allow up to 2 hours per pound and take it off sooner if done. This weekend, I was running late, so I set the WSM at 250 at the dome the entire cook and it still did not get completely done.
The results of judging showed up my mistakes, placing me around 15th place of 27 teams in three categories (the other being pork). My chicken was 4th, which also reflected a very good cooking experience.
Dale