10 pound butt

225-250 and figure on about 1.5hrs per pound, sometimes more and sometimes less, but at the very least you are looking at an all nighter for a butt that size. Last one I did was almost 9lbs and it took almost 14hrs. Don't forget, you will most likely hit the plateau for an hour or two but don't crank the heat up to try and push through it, kepp it steady, low and slow.
Good luck.

I would shoot for an internal temp of around 200*-205* cooking at around 225*. For a 10lb butt probably around 15hrs. You should go by internal temp of the meat though not time...

There are a bunch of helpful links on he left side of every page. One of them is for a time/temperature table.

For pulled Pork, I smoke between 225* to 240*. A very rough time frame is 1.5 hrs per pound. I wrap the pork in foil at 160* internal, and let the temp go up to 205* internal. Then I throw one more foil wrap around it, wrap that in towels, and let it sit in a cooler for at least 1 hr. I also preheat the cooler with hot water for 15 minutes before I put the pork in.

Here is a link to the table I mentioned:

http://www.wyntk.us/food/smoking-tim...eratures.shtml

Also, at the top of this forum, you'll see a link to "sticky" posts. Follow that link, and you'll find a great tutorial about making pulled pork.

Good luck with your smoke!