Installing a GM HEI Ignition Module into a 1976 280Z (which already had a ZX ignition) This article describes how to upgrade a ZX ignition module to a GM HEI module. In this particular case, the ZX ignition module happened to be installed in a 1976 280Z which had been upgraded to a ZX distributor/ignition module using the Atlantic Z Club instructions. The purpose of the HEI install was to fix a sudden engine cut-out problem and a jumpy tach problem. Heat Sink The first thing I needed was