really depends on how much the loin weighs... at 250 *. you're looking at about 45 minutes , to an hour a pound.... me , for one, I wouldn't cover it at all
Turkey breasts... is it one of those tied, netted up, turkey breast thingys??? if so, and it's 8 pounds, you might be looking at about an hour a pound as well
you might consider smoking both of them at higher temps , like 300* to reduce cooking time...
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