A spin gauge theory model using the Clifford algebra C_4,7 gives, without using the Higgs-Kibble mechanism, the salient features of the standard model plus appropriate gravitational Lagrangian terms. Uniform normalization of particle Lagrangian terms produces a formula relating all fermion masses to the W mass. For three families, neglecting mixing, the mass formula gives the top quark mass as 151.7 GeV. The inclusion of family mixing is expected to change this value only by the order of 0.1 GeV.