Monday, November 1, 2010
This photo is a shot looking straight down at the head under the valve cover. The rocker arms come off with the cover. The interesting thing to see here is the back and forth ridges on top of the head. These engines are air/oil cooled and this is where most of it happens. The oil that lubes the rocker arms and valves drains down on top of the head and flows around those ridges. It then drains down past the pushrods and lubes the cam before heading to the oil sump. Along the way it cools the top end off. If you overheat one of these motors it shows up here first. The oil gets cooked on to those ridges and makes a stinky mess.
I put the rest of the machine together today. I had to drill out the oil drain plug threads and re tap it to a bigger size. This is a common problem on machines here. People seem to have a habit of stripping the threads on the drain plugs. After finishing that I filled it up with oil and started it up. The engine ran great. There is a little bit of a rattle noise. I suspect it is from a slightly loose piston to cylinder fit. I did not replace the old scuffed up piston, I just cleaned it up with emery paper and honed the cylinder. It makes a little noise but will run fine.
Total time on the project, 8 hours.