To get the true black you have to set CMYK to the following colors:
C-75 M-68 Y-67 K-90:
The reason you don’t set all the values to %100 is because the printing will end up being muddy. However you should always check with your printer on how to get the best blacks possible. For example 4over.com the company we use for printing uses C-60 M-40 Y-40 K-100. And another company like Overnightprints.com uses 75% Cyan, 40% Magenta, 40% Yellow, and 100% Black. Generally if you set your values within 7% you will be fine. If you want to convert colors to Pantone in illustrator we wrote a short tutorial as well.