Insulated vertical reverse flow help

Hello. I just finished a vertical reverse flow build and gave it a test run the other day. I have a few questions. The cook chamber dimensions are 30"h x 16"w x 17"d. The firebox is 9"h x 16"w x 18"d. The chimney is 30"h x 8"w x 1"d. It's actually a bit bigger than that as extends past the top of the smoker. The entrance to the cook chamber from the fire box are two 17" x 1" entryways at the top of the cook chamber. The chimney entrance is (7) 3/4" holes at the bottom of the cook chamber. The air inlet a 1" ball valve located in the door to the firebox. I lit a chimney full of charcoal and put it in the firebox and added a few chunks of wood. It produced quite a bit of smoke, almost too much perhaps but the temp according the the thermometer in the door never got over 140 which I found hard to believe . I also noticed every once in a while a puff of smoke from the ball valve . All my numbers checkout in the calculator besides the air inlet. I have however seen this single valve design on several similar smokers on the web. My first thought is maybe more chmney inlets? Or possibly more inlet? Or could it be that the thermometer is just incorrect and its fine? Any help would be greatly appreciated, Thanks