Weird temp changes??

[Evotim]

So did my second overnight cook a few weekends ago... we had about 25+ people over so plenty of food to cook.
Decided to do 2 pork shoulders also some Armadillo eggs, smoked sausages, mac & cheese, slaw and salads. The girlfriend is great at slaw and salads which leaves me to concentrate on the rest.

I decided to do a bit of an experiment with the shoulders.. one with my normal rub recipe which i would spritz with apple juice and the other using a different rub recipe but this one i also injected and would baste to see the difference in end result. One weighed about 4kg and the other 5kg so thinking that it would take longer to cook the heavier one i put it at the top of the Excel where i thought it would be hotter.

Only the problem was it didn't quite work out like that which threw me.... I have 2 mavericks so had set one on each level. There didn't seem much difference at first when getting the smoker up to temp but once i'd put the meat on the bottom rack became hotter so after about a couple of hours of cooking i decided to swap them around. Temps seemed to level off a bit and then there was only a few degrees F difference. About 5 hours in and the top was hotter again and the smaller joint was steaming ahead temp wise. As it was about 2am i decided to leave it be til morning as i knew at some point it would hit the stall. Woke up at about 4am and the temps had almost levelled off again... confused to say the least.

Anyhow morning came and the smaller joint was looking slightly dry even though i was spritzing every few hours and as the top was yet again hotter than the bottom, decided to switch them, also thinking that the drippings from the top would help keep it moist.
For the rest of the cook from then on the top managed to stay hotter so the larger joint caught up and they were pretty much ready at the same time, one was 201f and the other 199f.

Can anyone tell me why the temps kept changing like that??

The other problem i ended up with was i think at some point i must have stupidly without realising the consequences closed all the bottom vents to stop a temp spike which i assume was the reason for a very slight creosote taste to the bark. Luckily though no one else noticed... Phew!! And even after pointing it out to my girlfriend she still couldn't tell.

As for my experiment the one i injected/basted was definately a lot moister so i think i may well continue to inject from now on.

https://drive.google.com/file/d/0B9ZJ1U ... sp=sharing

https://drive.google.com/file/d/0B9ZJ1U ... sp=sharing

https://drive.google.com/file/d/0B9ZJ1U ... sp=sharing

https://drive.google.com/file/d/0B9ZJ1U ... sp=sharing

[Evotim]

Can anyone help please?

Thanks

[YetiDave]

I'm confused... You're saying the top of the smoker kept getting hotter than the middle? Makes sense really, heat rises after all

[Evotim]

Well that's what i thought it would do but it fluctuated... the top started hotter as expected but then the lower rack was reading quite a lot hotter for a good hour or so, which is why i decided to swap the larger shoulder down to the lower rack and the smaller one to the upper rack.
Then a few hours later, about 2am the top became hotter again. By about 4am the temps on both racks were pretty much equal temps. Confused me too...
Strangely though, from the morning onwards the top stayed hotter the whole time so had to swap the shoulders around again to try to get them to finish cooking at the same time.

[Toby]

it all depends what you put in the water pan.

If you used the clay saucer method the bottom will be hotter as its closer to the heat source. they way you swapped the meat around meat that you put the hotter lump of meat at the top during the cook which would mean it would read hotter for a while.

Remember when you put your meat in, especially with different sizes the core temp will be different so it will take quite a while to level out.

If you close the bottom vents you actually choke the fire completely which will end up smouldering, smoking then going out. Every time you open the lid to swap meats around or to spritz you put the cook back by at least 20 mins so that another consideration.

A key consideration is to just let the cooker get on with things, forget multiple probes to check the pit temperature just keep the probes in the meat and watch them rise. Pork is very forgiving, if one is ready a couple of hours before the second just take it out and rest it.

[Evotim]

I've got sand in the water bowl so i'd imagine then it'd heat up like the clay saucer then and I did wonder whether the meat might have something to do with it also... makes more sense now.

Yes think i made the mistake of closing the bottom vents at one point... won't be doing that again and it didn't leave a good taste in my mouth.

Nice one, thanks Toby

[Toby]

no problem at all

[YetiDave]

Large chunk of meat in the hotter top = quicker internal temp rise = greater evaporative cooling
Smaller chunk of meat in the cooler middle = slower internal temp rise = lower evaporative cooling

Could be that