What do you line up the timing marks with on an aircooled vw beetle?

On an air-cooled VW Beetle, you line up the timing marks by aligning the mark on the crankshaft pulley with the timing notch on the engine case. Typically, this is done at the TDC (Top Dead Center) position for cylinder number one. Ensure the rotor in the distributor points to the corresponding spark plug wire for cylinder one as well. This setup ensures proper ignition timing for the engine.