Ignition Systems Guide for Big-Block Chevy Engines Distributors, Coils and Spark Plug WiresIgnition ControllersSpark PlugsBatteries and CablesStock big-blocks came with cast-iron Delco-Remy distributors until 1969 (Corvettes until 1974); then the switch was made to aluminum-bodied point distributors. In 1974, the HEI was introduced and was standard issue until computercontrolled EFI systems came out in 1987. The HEI is a unitized distributor with magnetic reluctors to trigger its internal control module and an ignition coil built into the large-diameter cap. It was and still is a very good design for most high-performance big-block..See more on chevydiy How to Time a Big Block Chevy | It Still Runs Connect the timing-light red lead to the positive terminal on the battery and the black lead to the negative. Connect the remaining end with the snap to the number-one spark plug wire, which is the closest wire to the radiator on the driver's side. Move all wires clear of all moving or hot parts and lay the timing light on the driver's fender.