A crank trigger will fix your issue. I had the same problem with my billet msd dist. on a sb. Installed a crank trigger, problem solved. I now have the same issue with another msd billet dist. In my 511. Timing goes backward about 3 or possibly 4 degrees as rpm is increased. Did not have this issue with the firecore dist. i removed because of a different issue with it . I use a timing light that takes 2 d cell batterys.