Thank you a lot sridhar_rajagopal, this works fine with an lcd screen i recovered from an old printer, it's a 1x16 characters lcd with 14 pins (14x1, no backlight), a VHX1610A.
I initially used this tutorial
from Mikey Sklar to wire everything up but used a resistor instead of a potentiometer (no need to adjust) and noticed the lcd didn't display the test correctly as It's considered to be 2 lines of 8 chars just like you (2x8). See here for more info : http://spikenzielabs.com/SpikenzieLabs/LCD_How_To.html
I wish the Adafruit_CharLCD api was updated on github to provide support for these characteristics. Initializing with lcd.begin(16,1) or lcd.begin(8,2) gave the same result (only shows the first 8 chars for each "line").
Note : Please use spaces instead of tabs in the code and be consistent !