Baby back ribs smoking time

[niceguy0427]

I have a model 2. I usually smoke 2 racks of baby backs for 5 1/2 hours at 235 degrees. They come out great every time. Will 4 racks take the same amount of time or will it take longer? Do I need to rotate the shelves during the smoke?

 

[SuperDave]

These smokers are very sensitive to air flow.  If 4 racks leave very little room for heat & air flow, time will definitely go up.  However, it you can arrange them such that there is space around them, they should be very close to normal cook time.  I would rotate shelves as racks of ribs laid flat can really shield the upper racks.

 

[40 caliber]

I have a SI2 and have done multiple smokes on ribs. I find that I can smoke 4 racks in 4.5 hours. I tend to put the analog switch at 250 and it seems to have a box temp of 235. when I use fewer ribs (1-2) it holds better at a guage temp of 235.  I was unable to cook 6 racks as the temp would not go over 185. it was also winter and 20 degrees out. I also may have restricted airflow jamming a 6th rack of ribs on 5 racks.
bottom line, I believe the analogs are a little more fickle. some folks told me they have no problem maintaining temp at 235 with 4 ribs. best I can say is have a thermometer to check internal temps and learn on your way.

To the other point on air flow. I  cut my full racks in half and put 2 halfs on each rack. I put them a little forward as the box seems warmer in the back. this is what I find works best. When you put forward however, make sure you don't touch or get too close to the probe in the back as it messes with the temp
(I may have also done this with the 6 racks but have not had a need to cook 6 again to figure it out)