A number of years ago I started on a 1/3 scale pocket valve Harley. I carved patterns and cast the crankcase conventionally in aluminum, and the flywheels in cast iron . I made knife and fork rods and dummy pistons from the solid so I could mock up the cylinders. My first set of cylinders were made in aluminum by stacking the wax fins fusing them together and then investing, burning out and pouring in a small chamber. When I moved on to the pocket and head I wasn't able to pull the silicon mold from the pattern due to the depth and dimension of the fins. One attempt with latex rubber failed due scorching the wooden pattern. I stalled out there and moved on to something else. These images were clawed back from photosuck, but I had started a thread over at AA. So after the experience I had with the brake calipers for the 9" Ford in the EDM I thought it was worth a try to pour a cast iron cylinder in the core molds like I used for the Indian heads and then use the EDM to cut the space between the fins.