Does that mean the spark plugs fires as the piston I traveling upward? That seems to be what it obviously is stating but I want to fully or at least partially understand this. If so that would mean that as the piston is coming up it is compressing the a/f mix from the bottom as the same mix is being burnt from the top. Correct? As if to imagine it compressing a spring that when it reaches the top of its stroke it pushes the piston downward. Thus 10 degrees btdc would be less advance and we would really consider the timing (in a technical sense) retard until the piston is past tdc and the plug fires while the position is on its way down?
"torque gets you off the line...& hp gets you over the line." - TTKeeper