[mreid]

An msd 8485 is for a 4 cylinder volkswagen, so that could be your problem!

Assuming you mean an msd 8584, as it is for a 351w, it comes with an iron gear and unless it was changed will not last long on a steel roller cam. However, there are some steel roller cam blanks that use an iron gear. You need to make sure that the gear is made of the material called for by the cam manufacturer.