Now the last one is more impressive. I got tired of doing little piddly things and bit off entirely too much to chew. This is the upper crankcase assembly. The lower crankcase is nothing more than the oil pan and oil pump, so it's not like there is a ton left to crankcase aside from this assembly, but the title of the drawing says upper crankcase so it's the upper crankcase. So far I have only been working on the cylinder head mounting studs and the crankcase casting itself, but once you look at it I think you'll understand why it has been taking me so long.
This is actually the third iteration of the model of the crankcase. Each time I spent forever just trying to figure out how all the various parts interact with each other and after about 200 or 300 features I figured out there was a better way I could have done it. So twice now I've scrapped the whole thing and went back to zero and restarted the model. That may sound like a huge waste of time, and maybe it was, but the model is a much leaner and meaner (and far more accurate) beast now because of it. So some of these pictures are actually of earlier iterations than the current one. Here are some in progress pics, wit the last couple being renders of how it looks right now.
Oh, and I got really bored with adding fillets at one point so I modeled the crankcase to cylinder head connecting studs, of which there are three types.
So that's where I'm up to so far. I hope to continue working on it and posting about it. I have created a blog, if that's still a thing these days, but if you are curious and want to see the models themselves I post my work to grabcad, a CAD model sharing site. You can go on there and download the models and see them yourself.