I've read that higher incubation temps can cause deformities like kinked spines, so when we incubated our eggs, we kept the dial right at 80ºF. They hatched less than three months later (I can't remember exactly when the female laid them) perfectly with no defects whatsoever. And it was a 100% hatching.
Some clutches have hatched fine incubated at 86ºF; some babies incubated at 83ºF have had kinked spines. It probably depends on the clutch and how sensitive they are to heat
Good luck with the clutch!