A typical E-core coil only has 0.5 Ohms or less primary resistance. The Pertronix I, needs 3.0 Ohms total resistance. A ballast is needed, or it will go poof, nothing there to limit the current. The E-core coil would result in a saturation current of 28A. A standard coil and ballast about 4.7A. Most ignition coils are rated between 4 to 7A, so the coil could be damaged too.