6421 Digital 6AL-2 Ignition Control Box
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MSD IGNITIONPART NUMBER: 121-6421

6421 Digital 6AL-2 Ignition Control Box

$43095$479.95You Save$49.00
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Performance
    Digital 6AL-2 Ignition Control
  • Per Spark Energy: 135 mJ
  • Built-in 2-Step Rev Limiter with Rotary Dials (No Chips)
  • Red

    WARNING FOR 6421: This product contains chemicals known to the State of California to cause cancer and birth defects or other reproductive harm.

    MSD is excited to announce the next generation of 6-Series ignition controls: the 6AL-2. This all-new ignition control combines a new housing, new digital controls, and more power in a sleek package. Inside the new cast aluminum housing you'll find an advanced micro-controller that manages the timing and RPM of the ignition. The spark output of the new box has been turned up to 535 volts of primary voltage with spark energy reaching up to 135 millijoules! The multiple sparks of the 6AL-2 burn in the cylinder for 20° of crankshaft rotation to ensure complete combustion. Two more great features are the rev limiters: one for high-end overrev protection and another you can activate off a clutch or transbrake to set a launch limit. This feature will help your car blast off the starting line! Adjustments are made via four rotary dials for 100 RPM increment control. Easily connects to nearly any 12-volt negative ground distributor system. Compatible with 4, 6 and 8 cylinder engines.

    Highlights
  • 100 RPM increment control using 4 rotary dials
  • Built-in 2-Step Rev Control with Rotary Dials
  • All-new housing and digital circuits
  • Accepts Hall Effect triggers
  • Managed by an efficient digital controller

    Operating Specifications
  • Spark Energy: 135 mJ per spark
  • Primary Voltage: 535 volts
  • Secondary Voltage: 45,000 volts (tested with Blaster HVC II Coil)
  • Spark Series Duration: 20° crankshaft rotation
  • RPM Range: 12,000 RPM with 14.4 volts
  • Voltage Required: 12 to 18 volts (negative ground)
  • Current Draw: 0.7 amp per 1000 RPM
  • Size: 7" L x 4" W x 2" H
  • Weight: 3 lbs
  • Not legal for sale or use on pollution-controlled vehicles.




  • All new housing, same reliable digital circuitry and performance
  • Built-in 2-Step rev control adjustable with rotary dials
  • Higher output with up to 135mJ of spark energy
  • Accepts Hall-effect, points and mag pickup triggers
  • Managed by an efficient digital processor
  • Emissions Note:

    This part is legal for sale and use on Emissions Controlled Vehicles, in all 50 states, when used in accordance with the manufacturer's application guide because it has a California Air Resources Board (CARB) Executive Order (EO) number D-722-2.

    CLICK THIS LINK FOR IMPORTANT CARB & EPA EMISSIONS INFORMATION ABOUT THIS PART

    High-Output Ignition Boxes for Maximum Spark Energy

    MSD 6-Series Ignition Boxes set the standard for quick starts, increased power, smooth idle, crisp throttle response, and reduced spark plug fouling. MSD Ignitions Boxes are available in several styles and install easily in multiple applications.

    Show More

    Unlock the true potential of your engine with the MSD 6-Series Ignition Control Boxes, a trusted choice for performance enthusiasts and racers alike. Whether you're cruising on the street or running hard at the track, the MSD 6-Series delivers the high-energy spark needed for complete combustion and maximum horsepower.

    Built with reliability and power in mind, the MSD 6 Series ignition boxes feature capacitive discharge (CD) technology that produces multiple sparks during the combustion cycle, resulting in smoother idling, quicker starts, and improved throttle response. This multi-spark feature is especially beneficial at lower RPMs, ensuring more efficient fuel burn and fewer misfires.

    The MSD 6 Series Ignition units are housed in a durable, vibration-resistant aluminum case that’s ready for the rigors of street or strip. Easy to install and compatible with a wide range of engines and distributors, this versatile ignition box is a go-to upgrade for those looking to enhance overall engine performance.

    Whether you're running naturally aspirated or forced induction, the MSD 6 Series Ignition Control gives you the confidence of consistent spark delivery at high RPMs, helping your engine perform at its peak when it matters most. With several models available—including options for street, marine, and racing applications—there’s a 6-Series box tailored to your build.

    Choose MSD for proven ignition technology that boosts performance, improves efficiency, and ensures your engine fires strong every time.

    The MSD 6 Series Ignition Control Boxes are a cornerstone upgrade for performance enthusiasts seeking stronger spark energy, improved combustion efficiency, and reliable high-RPM performance. Designed to deliver multiple sparks at lower RPM and a powerful single spark at higher engine speeds, MSD 6 Series Ignition Control Boxes help maximize horsepower, throttle response, and overall ignition stability. Whether you’re building a street-driven muscle car or a dedicated drag racing machine, upgrading your ignition system is one of the most effective ways to improve engine performance and reliability.

    A high-performance ignition control box ensures a more complete fuel burn, which translates to smoother idle quality, quicker acceleration, and reduced misfires under load. For modified engines with increased compression ratios, aggressive camshafts, or forced induction, a robust ignition system is essential.

    Performance Benefits & Key Features

    MSD 6 Series Ignition Control Boxes are engineered to provide capacitive discharge ignition (CDI), delivering high-voltage spark output and consistent performance across the RPM range. Performance enthusiasts often evaluate ignition systems based on spark energy, rev limiter capability, wiring compatibility, and durability. The multiple spark discharge feature enhances combustion at lower RPM, improving drivability and fuel efficiency in street applications.

    These ignition control boxes are built with rugged housings to withstand vibration, heat, and demanding driving conditions. Adjustable rev limiting functions help protect engines from over-revving, making them ideal for both street performance and competitive racing environments. Improved spark intensity supports stronger combustion in high-compression and boosted engine combinations, contributing to enhanced torque capacity and throttle response.

    MSD 6 Series units are commonly used in street performance builds, drag racing cars, circle track applications, and classic muscle car restorations seeking modern ignition reliability.

    Fitment, Compatibility & Applications

    MSD 6 Series Ignition Control Boxes are compatible with a wide range of GM, Ford, and Mopar engines when paired with appropriate distributors and ignition components. Popular applications include Chevrolet Camaro, Chevelle, Ford Mustang, Dodge Challenger, and various small block and big block V8 platforms.

    Designed to integrate with aftermarket distributors and performance coils, these ignition systems provide flexibility across carbureted and select EFI applications. Proper installation ensures seamless compatibility and optimal performance gains.

    If you’re ready to strengthen your ignition system and unlock consistent high-RPM power, explore the MSD 6 Series Ignition Control Boxes at JEGS and equip your build with proven ignition technology trusted by performance enthusiasts worldwide.

Part TypeIgnition Box
Product LineMSD 6-Series Ignition Control Boxes
BrandMSD IGNITION
Package Height2.7
Package Width9.6
Package Length10.9
Weight3.25 PG
Part CategoryPerformance Parts
Ignition Box OutputCapacitive discharge
Rev LimiterYes
QuantitySold individually
Cd Voltage Output To Coil535 V
Spark Output (Millijoules)135 Millijoules
Part FitmentUniversal
Ignition Box ColorRed
Rpm12,500
Vendor Part Number6421
Package Qty1
Package TypeEA
No Questions
No Reviews

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Some parts are not legal for use in California or other states with similar laws / regulations
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