[en] The influence of non-central interactions is investigated in mass 18 to 22 nuclei. The effect of non-central components in the realistic matrix elements of Kuo is evaluated in mass 18, 19 and 20 nuclei. A phenomenological interaction is constructed to reproduce the results obtained with the Kuo Hamiltonian and compared with an interaction fitted to experimental levels. The fit to experimental levels requires a repulsive triplet even tensor force. (Auth.)