The response of an overhead cam valvetrain system has been accurately simulated using the Advanced Continuous Simulation Language (ACSL). This approach is unique by using a software program to solve the system equations while others have derived codes to perform these calculations. Simulation variables include cam lift velocity function, valve spring stiffnesses and damping coefficients, stiffnesses of other valvetrain components, and cam speed. Simulated results closely agree with actual valvetrain test data. Natural frequencies obtained from the valvetrain simulation match those predicted by spring design theory and finite element analysis. Since the cam lift function and other components' properties are easily modified, this computer simulation simplifies the task of designing valvetrain systems by providing meaningful and reliable system response predictions quickly.