I Think I Figured Out Why My Car Is Slow!!

well, here it is... I took my old harmonic dampner off and put on the new one. When I put the new one on, I found that the timing (w/spout out) is at 18*... so I back it down to 15* and get a little bit of power, hardly noticeable. I don't know what to do now, do I have to degree the cam?