We demonstrate that the defect mode in the bulk plasmon-polariton gap of one-dimensional defective metamaterial photonic crystals can be used to achieve a giant enhancement of more than four orders of magnitude in the second harmonic (SH) conversion efficiency only by changing the incidence angle. Furthermore, the one-dimensional photonic crystal may be designed in order for the SH wave to coincide with the edge of the Bragg gap or with the defect mode inside this gap, in which case the enhancement is even higher. Because of the robustness of the bulk plasmon-polariton gap to scaling effects, the present proposal may inspire different routes for frequency upconversion, signal filtering, and switching photonic devices.