I can’t make any more progress without getting the approximate position of the nosebowl pinned down. I spoke with the folks at American Propeller about the dimensions of the Whirlwind spinner, and they sent me some nice CAD pictures of two options. The short answer is that the aft edge of the spinner is pretty close to the front of the prop flange. Since the rubber baffle seal on the front of the baffle parts will allow for some adjustment, I only need to get a rough idea of where the nosebowl will fall. Step one: assemble the halves.
This piece of 1/4″ OSB should do nicely. I measured and drilled all 6 holes, then held it up to see how I did:
I enlarged a couple of the holes so that I could get small c-clamps in to hold the OSB to the flange.
With a rough idea of where the nose bowl will end up, I started working on the top for the air filter housing. I’m using the Vans Filtered Air Box (FAB) because it has several great design features. For instance, the filter element is reusable, and available from non-aviation sources. Air from the carburetor heat source is still filtered, eliminating the need to turn off the carb heat after landing at dusty/grassy places. And best of all, it eliminates the need for that expensive and troubled box from aircraft spruce that everyone else is using. I started by cutting a hole in the FAB top so to clear the bump on the bottom of the carb.