well your not using a ford box ? msd box ? all the msd s i used and that s many some were i was told to use 035 to 045 this is more to keep the plugs from blowing out with hi cr .opening up the plug gap your trying to do what? better burn. building more coil out put . spark dwell time ? and use a finite tip plug$$ that will do zip for you ?? with the msd you have this is multiple spark. no need to open up the gap but i could be way wrong but it works for me