This modification replaces the factory Honda ignitor module with a solid-state circuit. This setup is designed to provide a clean, reliable trigger signal for aftermarket ignition boxes, such as MSD or Crane units.

Technical Overview#

The factory ignitor is replaced by a transistor-based circuit that mimics the switching behavior required by aftermarket ignition controllers.

Note

The ZTX857 transistor is recommended due to its physical size, which allows it to fit within the distributor housing. However, any power Darlington NPN transistor capable of handling the required current (typically 2+ amps) is a suitable substitute.

Schematic#

Implementation Details#

When building the circuit, ensure all connections are heat-resistant and vibration-proof, as the distributor environment is subject to high temperatures and constant mechanical stress.

Caution

Ensure the transistor is properly insulated from the distributor housing if it is mounted to the metal casing to prevent short circuits. Use thermal paste if mounting to a heat sink surface to ensure longevity.

Tip

Verify the trigger voltage requirements of your specific aftermarket ignition box (e.g., MSD 6A/6AL) to ensure the circuit output matches the controller's input specifications.