iirc set it retarded it lowers the powerband down the scale, gives a bit more oomph n torque but looses a bit of top end
and advancing is the opposite, looses a bit of bottom end, pushes the powerband up a bit and gives a little more oomph at the top end.
if its an aftermarket cam (iirc also) kent cams are ground to a 4degree advance on standard cams anyway.
just be careful not to crank it too far and bend ur valves!!!