I'm picking up from the this alum.repair idea posted, few years back. Got an idea, possibly helping with the heat range needed, near 1200 deg. to weld alum. cast properly. In the video their using a bbq grill to heat up part, near 500 deg along with a torch, yet reading the replies, the oven is near that temp but not the part, which would be something  less. I'm thinking, what about building a hot wood fire, with a rack above it and setting a metal plate on the rack a little larger than the part to be welded to set part on which would direct the flames around the part indirectly. Then cover with a dome of some kind containing heat inside with a temp gauge on the part or on the metal plate and when the temp reaches the desired melting point for alum welding rod to take (you might not even need the torch) then hopefully it would run deep into the part body and not just sit outside/around the break making for a stronger hold? Maybe trial and error on scrap pcs first. I'll try it as soon as I can find some cast alum. and reply back or possibly one of you, have already tried and give your thoughts on heating part hot enough for a good weld. My only concern might be distortion to the part because of the extreme heat, yet using the torch gets that hot, too!

Fortunately i don't need a weld, yet in the past I could have used one, so for now I'll just practice doing a weld, then try beating it to death to see how well it holds. Still looking for scrap alum cast to try. I've got some old alum rods, yet I don't know what kind and if they have the flux coating.