MSD 8739 Two-Step Module Selector for Rev Controls and Timing Computers

The MSD 8739 Two-Step Module Selector gives performance and racing enthusiasts the ability to run two separate RPM or timing retard modules, switching between them on demand during a run. Whether you're managing a launch rev limiter off the line or protecting your engine at high speed, this selector puts precise RPM control at your fingertips.

Key Features:

• Allows selection between two independent RPM limit or timing retard modules, each activated at different times during a run
• Modules are triggered by applying 12 volts to the corresponding activation wire — no manual switching required
• Default module (Module 2) remains active when no voltage signal is present, providing a built-in high-RPM safety limit
• Compatible with MSD Soft Touch Rev Controls and any MSD Timing Control that uses plug-in modules
• Can be used in a retard module socket for activating multiple timing retard stages — ideal for multi-stage nitrous systems
• Works with an MSD RPM Activated Switch to trigger a shift light at selectable RPM points
• Includes launch rev limiter and high-speed rev limiter capability
• Legal for use on emissions-controlled vehicles, uncontrolled vehicles, and racing-use-only vehicles
• Constructed from durable black plastic housing

What's Included:

• 1 — Two-Step Module Selector (PN 8739)
• 4 — Mounting Screws
• 1 — Parts Bag with Wiring Terminals

Note: RPM modules are not included and must be purchased separately. Compatible with analog MSD systems only. Do not use solid-core spark plug wires with any MSD component.