  Accurate quartic anharmonic force fields for CF$_4$ and SiF$_4$ have been
calculated using the CCSD(T) method and basis sets of $spdf$ quality. Based on
the {\it ab initio} force field with a minor empirical adjustment, the
vibrational energy levels of these two molecules and their isotopomers are
calculated by means of high order Canonical Van Vleck Perturbation Theory(CVPT)
based on curvilinear coordinates. The calculated energies agree very well with
the experimental data. The full quadratic force field of CF$_4$ is further
refined to the experimental data. The symmetrization of the Cartesian basis for
any combination bands of $T_d$ group molecules is discussed using the circular
promotion operator for the doubly degenerate modes, together with tabulated
vector coupling coefficients. The extraction of the spectroscopic constants
from our second order transformed Hamiltonian in curvilinear coordinates is
discussed, and compared to a similar procedure in rectilinear coordinates.
