Last weekend, Jeff and I moved the second wing of his Kitfox out of the paint booth, so I had somewhere to spray the manifold heater for the Model A. A couple of new bolts later, and everything’s installed:

As you can see, it’s a pretty simple heating mechanism. Air flows through the radiator, enters the manifold heater (which is sitting on the exhaust manifold, so it’s hot), then enters the cabin. Works alright as long as you’re not moving too fast or too slow. But it’s better than nothing and didn’t require any additional modifications, since one of my relatives had already installed the firewall opening. The other option is to have a hot water radiator mechanism, but that means running water lines from the radiator to the cabin, which seems like a bad idea.