We use the multiconfiguration Dirac-Hartree-Fock (MCDHF) method combined with the relativistic configuration interaction approach (GRASP2K) to provide a consistent set of transition energies and radiative transition data for the lower n = 3 states in all Cl-like ions of astrophysical importance, from Cr VIII to Zn XIV. We also provide excitation energies calculated for Fe X using the many-body perturbation theory (MBPT, implemented within FAC). The comparison of the present MCDHF results with MBPT and with the available experimental energies indicates that the theoretical excitation energies are highly accurate, with uncertainties of only a few hundred cm(-1). Detailed comparisons for Fe X and Ni XII highlight discrepancies in the experimental energies found in the literature. Several new identifications are proposed.