You can expect those homemade adobe brick to fracture and disintegrate. Normally I would recommend fire brick to at least serve as a lining as they hold up to the stresses of repeated hot/cold cycles. If you are able to fashion bricks from
local materials, there is no concern about the cost. Try it out. When the adobe fails, you can replace with more of these homemade adobe bricks. If it is worth your investment of time and effort, go for it.