To add just a little to what code3rrt said, In my kettle to get 250 I find that the bottom vents need to be open 1/8 inch and the top either full or 3/4 open. Cover the unused portion of the coal grate with foil this will allow for a more precise temp control because all the intake air must pass up & through the fire. Bury some of those wood chunks in the pile and let the coals warm the wood as it ignites this will keep the "Sweet Blue" rolling through the cook. By the way your ribs look marvelous.
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