Document nkzjydBnjBZwmL73DyKXoN0Y8

General Motors H.E.I. and E.T.S. electronic ignition systems use ^ , a silicone based bonding between the control module and the basest the distributor. substance is used to assure a good electrical ground een the two surfaces. It also serves as a heat sink to help the control module's operating temperature within a safe limit. This silicone bonding is very similar to the silicone grease used in the electronics field and has been around for quite some time. According to Delco, the grease is a #8101 Z5 silicone com pound manufactured by the G.C. Electronics people. General Electric has a similar compound that can be used. The part numbers are G 641 and G 642. Dow Coming's compound is #340 and #341, and of course, ECHLIN packages this grease with each control module. When replacing the control module, (Echlin part # TP 45), in vehicles equipped with the H.E.I. and E.T.S. electronic between the control module and the distributor base plate. Failure to do so can result in a very short control module life and a complete failure of the vehicle's ignition system. HEI COIL WIRING Upon replacing the ignition coil in an eight cylinder General Motors vehicle equipped with the High Energy Ignition System, it is sometimes required to replace an ignition coil with two wires with an ignition coil with three wires attached. A considerable amount of confusion has been generated in the field as some mechanics, upon their first installation, were unsure of where the extra black wire should be attached. Because of the improvements between the two wire and three wire coil, it is now necessary to provide a "ground" when instal ling the newer three wire coil. The black ground wire should be attached to a coil mounting bolt closest to the black ground ing wires exit from the coil. The other two wires are attached to the distributor cap connection housing in the same location that the original wires were attached. PRE 1975 AFTER 1975 A CHun. 4 Printed in U S.A.