A is for advance which is before TDC, not after. R is retard which is after. Your crankshaft will appear to rotate clockwise when viewed from the front of the engine. Adjusting the timing so the mark moves towards the passenger side of the engine will advance the timing. You will turn the distributor counter-clockwise to advance the timing. If your timing is close to where it should be, the engine rpms will increase as you advance the timing and decrease as you retard.