A numerical approach of dynamic contact analysis is presented and applied to the simulation of an axisymmetric valve-cotter system in a motorcycle engine. The contact and the Coulomb friction conditions are described exactly by linear complementarity relations, and discretized dynamic equations are derived. A Newton-type method is used to solve the resulting complementarity problems. This implementation has the advantage of not requiring any user-supplied parameter values to satisfy the contact and friction conditions, compared to penalty or other function-smoothing algorithms. Detailed histories of contact forces and contact status obtained show the applicability of this approach to complex frictional contact problems.