Usually it discolors and fades, rather than peeling or burning off completely. Unless you block the heat crossover passage in the heads, it will continue to fade.
I've had better success with Hirsch enamel, and even the Duplicolor didn't let go like that. In this area, the thinnest possible application of paint is best. Here's a pic of mine, a year after painting with Duplicolor.
Vikki 1969 Goldenrod Yellow / black 400 convertible numbers matching