A method for making a light alloy foundry part that includes at least one piping supported by a wall of the part. The method includes making the piping, making a mold reproducing a shape of the part without the piping, positioning the piping in the mold, and casting a metal for making the part. At least a portion of the piping is subjected, prior to the installation thereof in the mold, to a surface-processing to generate a thermal barrier between the portion of the piping and the casting metal, the mold including at least one hollow location around the piping for making a bridge for supporting the piping and extending from the wall of the foundry part.