Why when I "power" time my engine I have way too much advance (50*)ish when i back it down to 40* it runs well but not as good as when it's cranked up. most people tell me 40* is way too much. I know everyone is going to say check your timing mark, I did and it's within a couple of degrees. wtf ? I think it's a combo of high altitude, maybe too much octaine (can't quite run on pump gas 427bbc 11.6 to 1) so I run half 110 and half pump gas, open chamber heads(broxix bb2+heads ) . I guess what my question is should I power time it or listen to the light?