School me, what makes a motor a Wedge?

Right you are friends. A wedge has a wedge shape with the valves in a row. The Hemi is a hemisphere shape or a dome shape with the valves on opposite sides with the spark plug in the middle. The poly is semi domed shape like the hemi but the valves are ofset for more efficient flow. It also makes them cheaper to produce. Here's a interesting article about the poly and the Hemi. http://www.streetrodderweb.com/tech/0805sr_vintage_engines/index.html

Here's a visual of the differences of the big 3. The first image is the Hemi. The second is the Poly, and the third is the wedge.