MSD RPM Three Step Module Selector 57105BK 85 and earlier Small Block

85 and earlier Small Block Chevys

1968-1969 Mercury Cougar

Idle / 3500 RPM

Adjustable from 12-1/2" to 17-1/2"

Intake/Exhaust Valve Size

MSD RPM Three Step Module Selector 57105BK 85 and earlier Small BlockThe MSD Module Selectors allow you to choose two or three different rpm limits that can be activated at different times. With this ability, the possibilities are endless. As an example, well use a drag car with a Three Step Module Selector plugged into the rpm socket of a 7AL 2 Ignition. The different rpm modules are activated when 12 volts are applied to a corresponding wire. By connecting one wire to the line lock circuit, one module will be