cam timing

[justinburnett]

recently while rebuilding a 400 small block, I ran into a situation where the old timing gear was 4 degrees advanced. I was told that I should set it back to 0 when I put everything back together. I never thought to ask why, so I though maybe someone could explain it to me. What would happen if you had +4 cam timing? what does that cause to happen? valves open earlier on the stroke? What does this mean as far as power and such? I can't see why it would be a benefit.
Just have time to be curious at the moment whereas before I was scrambling to get the project done. Thanks.