I'm using a black and white bump map image to carve a image from an object but when I change the height it only bumps a little. If increase the height nothing really changes. How can I change the height/depth of my bump map?
At first of course, use an app like CrazyBump or else to convert your picture to a DISP picture.
Then: Image Texture node (Non-Color Data mode) -> (Color Output) -> Height input of a Bump node -> Normal input of a Diffuse node -> Material Output node. Play with the Strength value of the Bump node to increase the effect.
As Cegaton said, if necessary, you can increase the effect with a Converter > Math node (Multiply mode) between the Image Texture and the Bump (you could also try a Converter > ColorRamp node between the Bump and the Diffuse).
Here I've used your file, set a simpler material, and played a bit with the different values of CrazyBump, it gives a bit of blur and grey, you can get something better than what you can get with a simple B&W picture, but you can't simulate a deep engraving, especially if you don't have any image texture that goes along and that could help to fake it...
BlenderForNoobs has made a video on this topic, you can see that you can only fake a slight engraving: https://www.youtube.com/watch?v=wWB5XVK7-VI&