I'm not sure if wolfpack had to modify his lower cowel for his carb heat design.
I designed something different from wolf packs and I will have to modify the lower cowl slightly.
technically I can get the lower cowl on but it is a pain so I will give the heat box a little more room so I don't have issues putting on the lower cowl.
You can visit my carb heat design and install at
http://www.onexmike.org. and find Carb heat box in the menu.
I was told by Scott Casler that the Zenith carb doesn't like direct ram air so like the Aerovee carb it just gets its air inside the cowl.
I have a nose wheel which created the tight fit because I had to modify the intake Y to move the carb forward .If you have a tail dragger I'm positive you would not have to modify the cowl.
Mike