Does anyone know at what temperature Aluminum Bronze begins to harden like this? It's on the exterior of the block under the intake manifold. It shouldn't see temperatures higher than 250 degrees F.

Hey everyone, I'm a fairly novice TIG welder but have been having good success welding mild, carbon, stainless, and aluminum lately. I've ran into an issue with the engine block on my race car cracking, right along an oil gallery, and i want to tig weld the crack shut. In a frantic effort the day be...