The rotation-bending-internal rotation Hamiltonian for quasi-symmetric top molecules with a single rotor [A. Wierzbicki, J. Koput, and M. Krȩglewski, J. Mol. Spectrosc.99, 102-115 (1983)] is used to calculate the correlation diagrams between the energy levels of the SiH 3NCO-type molecules in the symmetric and asymmetric top limits, and to predict various features of the microwave spectrum through trial calculations. The height of the barrier to linearity was varied from 0 to 6500 cm -1. For the barriers 0, 31, and 139 cm -1, the effects of hindered internal rotation are studied and several (∆ l = 3, ∆ k = 0) resonances are found. In some cases almost all the microwave transitions from a given vibrational state can be perturbed.