4 racks of ribs, two different results

[taco]

So...

I had four racks of ribs. All were treated exactly the same, same rub at the same time, put in the smoker at the same time. Used the 3-2-1 method.

The two racks on the bottom rack of the smoker were nice and tender, the two racks that were right above the lower two were very tough.

During the last hour, I switched the ribs on the racks, so that the top two were now on the bottom rack in the smoker.

Can anybody help me with where my mistake was?

 

[demosthenes9]

 
So...

I had four racks of ribs. All were treated exactly the same, same rub at the same time, put in the smoker at the same time. Used the 3-2-1 method.

The two racks on the bottom rack of the smoker were nice and tender, the two racks that were right above the lower two were very tough.

During the last hour, I switched the ribs on the racks, so that the top two were now on the bottom rack in the smoker.

Can anybody help me with where my mistake was?

The two racks that started out on top were undercooked.   The ribs on the lower rack got more heat for 5 hours and the 1 hour after swapping positions wasn't enough for the others to catch up.

How to fix is to do the rib rotation before foiling.   Use 3 2 1 as a guideline of sorts.  With rotation, it might be 4 hours before the ribs are ready to be foiled, then it might only be 1 hour in the foil.   You just have to play around with it.

 

[taco]

Well, now that makes perfect sense. My common sense must have taken a break, thanks for allowing me to borrow yours.

So, switching racks will resolve that issue for me. Should it be done half way thru each "leg" of the 3-2-1?

 

[taco]

Thanks for the help, just saw that you had already answered. Told you my common sense was gone.

 

[valleypoboy]

FYI,
Maybe I live in one of those "Mystery spots", but I've always found that the meat on the TOP of my cooker finishes first. This was using a vertical propane smoker. I've never understood why, perhaps air currents from going around the water bowl or radiant heat coming back down from the top of the unit?
If I'm doing 2 butts I put the larger one on the top, hoping they will finish around the same time, but rarely does that happen. The larger one on the top still usually finishes first.

 

[demosthenes9]

 
Thanks for the help, just saw that you had already answered. Told you my common sense was gone.

All good Taco.  

FYI,
Maybe I live in one of those "Mystery spots", but I've always found that the meat on the TOP of my cooker finishes first. This was using a vertical propane smoker. I've never understood why, perhaps air currents from going around the water bowl or radiant heat coming back down from the top of the unit?
If I'm doing 2 butts I put the larger one on the top, hoping they will finish around the same time, but rarely does that happen. The larger one on the top still usually finishes first.

It all depends on quite a few variables.  Are you using water in the pan ?  Sand ?  An empty foil lined pan ?  How big is the pan ?  How large is your chip box ?  Where is the chip box in relation to the heat source ?  How much heat is the chip box giving off ?   How high above any obstruction is your lowest shelf ?  Where is your smoke stack / upper vent situated ?  How much heat does it allow to escape ? 

All of those questions come into play when your smoke chamber is completely empty.  Once you start loading meat on shelves, the thermal dynamics will be altered.  If you put a big brisket or 2 large racks of ribs on the bottom shelf, that will probably affect the air flow within your chamber and cause the hotspots to move.