John,Depending on how much fat and gristle...butts can run 1-3 hours per pound when cooking at 250deg +-......so 8lbs with a lot of fat at gristle could take 20 hours..but another thing to consider is ....were they inhanced?..If so you can have 12% solution added to the butts....And this could cause a longer cook if you took them out of a fridge that had the meat at 40 deg....One thing he didn't metion was what temp the meat was when he took it out of the fridge...Heck it could of had the center at 34%...just a thought