heres a pic of the 'cracker' boxes i make..... dual 'tuned' flasher relays( change resister inside to spark quicker..approx 20 times a second)..two relays used for safety,incase one screws other still works.... grey n red wires to dash... black n red to coil....green n brown to fuel pump n fuel shut off valve (if used)...led on switch to show operation n monitor sparking.

(lighter in foreground to show approx size..)