This is the stock (0°) dowel to locate the sprocket to the camshaft on the Ford 1600 Kent engine. Dowels are also available in 1 to 9° offset (Part No. 161-40-Size) to advance or retard cam timing.
If your sprocket has an oversize (0.437") hole, your engine was set up for this dowel plus an offset "button" (a ring that fits around the dowel). Offset buttons are no longer available, but you can use an offset dowel with your existing button. If your button is missing, you will need to replace the camshaft sprocket.