MSD 6520 User Manual

INSTALLATION INSTRUCTIONS 1
AUTOTRONIC CONTROLS CORPORATION • 1490 HENRY BRENNAN DR., EL PASO, TEXAS 79936 • (915) 857-5200 • FAX (915) 857-3344
MSD Digital 6 Plus Ignition Control, PN 6520
Parts Included:
1 - MSD Ignition 1 - Harness, PN 8860 1 - Parts Bag, ASY 19864
WARNING: During installation, disconnect the battery cables. When disconnecting the battery always
remove the Negative cable first and install it last.
Note: Solid Core spark plug wires cannot be used with an MSD Ignition.
LED INDICATOR
There is an LED that monitors the status of the Ignition. The LED monitors several parameters of
the ignition including trigger signal, low voltage and high voltage.
OPERATION AND FEATURES
Note: Do not use digital or dial back timing lights.
DIGITAL OPERATION
The MSD Digital 6 Plus uses a high speed RISC microcontroller to control the ignition’s output
while constantly analyzing the various inputs such as supply voltage, trigger signals and rpm. The
high speed controller can make extremely quick compensations to the output voltage, multiple
spark series, timing and rpm limits while maintaining accurate timing signals to within 1° and 1%
of the rpm limits. The circuits and controller of the Digital 6 Plus have been thoroughly debounced
and isolated to create protection against Electro Magnetic Interference (EMI).
CAPACITIVE DISCHARGE
The MSD Digital 6 Plus features a capacitive discharge ignition design. The majority of stock
ignition systems are inductive ignitions. In an inductive ignition, the coil must store and step up
the voltage to maximum strength in between each firing. At higher rpm, since there is less time to
charge the coil to full capacity, the voltage falls short of reaching maximum energy which results
in a loss of power or top end miss.
The MSD Ignition features a capacitor which is quickly charged with 520 - 535 volts and stores
it until the ignition is triggered. With the CD design, the voltage sent to the coil is always at full
power even at high rpm.
MULTIPLE SPARKS
The MSD produces full power multiple sparks for each firing of a plug. The number of multiple
sparks that occur decreases as rpm increases, however the spark series always lasts for 20° of
crankshaft rotation. Above 3,300 rpm there is simply not enough “time” to fire the spark plug more
than once, so there is only one powerful spark.
PROTECTION
The MSD Digital 6 Plus has a built in reverse polarity protection circuit. This will protect the ignition
in the event of wrong connections. It will also shut off for protection from a surge in power. The
ignition will still operate once the surge or polarity is corrected.

MSD 6520 Specifications

General

Brand	MSD
Model	6520
Category	Microcontrollers
Language	English

Summary

OPERATION AND FEATURES

DIGITAL OPERATION

Microcontroller-based control analyzing inputs for accurate timing and output compensation.

CAPACITIVE DISCHARGE

Capacitor charging system providing full power output at all RPMs, unlike inductive systems.

MULTIPLE SPARKS

Produces multiple sparks per plug firing, decreasing with RPM, for improved combustion.

PROTECTION

Built-in reverse polarity and surge protection circuits to safeguard the ignition unit.

LED INDICATOR

Monitors ignition status, including trigger signal, low voltage, and high voltage.

REV LIMITER

RETARD CONTROL

Single stage retard adjustable up to 9.9 degrees, activated by 12 volts on Pink wire.

START RETARD FEATURE

Retards timing by 20° during cranking until 800 RPM for easier starting.

CYLINDER SELECT FEATURE

Allows programming for different cylinder counts; factory set for 8-cylinder.

GENERAL INFORMATION

BATTERY SPECIFICATIONS

Operates on 12V negative ground systems, tolerates momentary 24V, and requires 9-18V for full output.

COIL COMPATIBILITY

Compatible with most stock and aftermarket coils; Blaster Coils recommended.

TACHOMETER INTERFACE

Features a Tach Output Terminal for RPM signals; may require adapters for some vehicles.

SPARK PLUGS AND WIRES

Spark Plug Wire Routing and Gapping

Guidelines for routing spark plug wires and selecting/gapping spark plugs for optimal performance.

MOUNTING

WIRING FUNDAMENTALS

PROGRAMMING OPTIONS

CYLINDER SELECT SETUP

Program the ignition for different cylinder counts using the rotary switch; factory set for 8-cylinder.

START RETARD SETUP

Configure the 20° timing retard during cranking until 800 RPM for easier starting.

MAGNETIC PICKUP COMPENSATION

Provides timing compensation for different trigger pickups for more accurate signals.

ADVANCED REV LIMITER FEATURES

MAX LIMIT ADJUSTMENT

Sets the overrev rpm limit, adjustable in 100 rpm increments via rotary switches.

2-STEP REV LIMITER

Activates a secondary rpm limit when 12 volts are applied, overriding the max limit.

RETARD STAGE ACTIVATION

TROUBLESHOOTING GUIDE

LED INDICATOR INTERPRETATION

Interprets LED flashes for battery voltage issues, surge conditions, or trigger signal confirmation.

TACH/FUEL ADAPTER REQUIREMENTS

Information on tachometer compatibility and the need for MSD Tach Adapters for certain vehicles.

SPECIFIC VEHICLE ISSUES

FOREIGN VEHICLE NO-RUN SOLUTIONS

May require a Tach/Fuel Injection Adapter (PN 8910 or 8910-EIS) for foreign vehicles with EFI.

INOPERATIVE TACHOMETER DIAGNOSIS

Troubleshooting steps for non-functioning tachometers, including checking tach output and using adapters.

BALLAST RESISTOR BYPASS PROCEDURE

Guidance on bypassing ballast resistors when using the MSD White wire trigger.

ENGINE RUN-ON PREVENTION

Using a diode to prevent voltage feedback and engine run-on in older vehicles with external voltage regulators.

ENGINE PERFORMANCE PROBLEMS

PREVENTATIVE INSPECTION CHECKLIST

Inspect plug wires, coil connections, and wiring for damage, corrosion, or loose connections.

SPARK TESTING PROCEDURES

Step-by-step guide to test for spark using White wire or Magnetic Pickup trigger methods.

SPARK TESTING AND NO SPARK DIAGNOSIS

NO SPARK TROUBLESHOOTING STEPS

Steps to diagnose no spark, including wiring checks, coil substitution, and voltage checks.

MSD SYSTEM WIRING SCHEMATICS

Points/Amplifier Ignition System Wiring

Diagram for connecting MSD to points or amplifier ignition systems, including coil wiring notes.

MSD Distributor/Crank Trigger Wiring

Diagram for connecting MSD to MSD distributors or crank triggers using magnetic pickup.

MSD SYSTEM WIRING SCHEMATICS (CONT.)

MSD Distributor PN 8360 Wiring

Wiring schematic for connecting the MSD to an MSD Distributor PN 8360.

Dual MSD Ignition System Wiring

Diagram illustrating a dual MSD ignition setup with two MSD Blaster coils.

MSD SYSTEM WIRING SCHEMATICS (CONT.)

MSD Timing Control Integration

Diagram for using MSD with an MSD Timing Control and points/amplifier ignition.

Drag Race Setup with Timing Control & Two Step

Diagram for a drag race setup including timing control, two-step selector, and retard circuit.

GM IGNITIONS WIRING

Dual Connector Coil Wiring

Diagram for wiring MSD to GM vehicles with a dual connector coil, including splicing notes.

1996+ Single Connector Coil Wiring

Diagram for wiring MSD to 1996+ GM vehicles with single connector coils without using a harness.

GM IGNITIONS WIRING (CONT.)

MSD Wiring Harness Installation (GM)

Diagrams for connecting MSD using PN 8876/8877 harnesses to GM vehicles with dual or single connector coils.

GM Wiring with Harness and Timing Control

Diagram for connecting MSD with harness and timing control to GM vehicles.

GM HEI DISTRIBUTOR TYPES

GM Large Cap HEI Distributor Identification

Identifying GM HEI distributor types (4, 5, 7-pin) and potential hesitation issues on 5-pin models.

GM HEI IGNITION WIRING

4-Pin Module (Magnetic Pickup Trigger)

Diagram for wiring MSD to GM HEI 4-pin modules using magnetic pickup trigger.

GM HEI IGNITION WIRING (CONT.)

5 or 7-Pin Module (Amplifier Trigger)

Diagram for wiring MSD to GM HEI 5/7-pin modules using amplifier trigger.

FORD IGNITIONS WIRING

DuraSpark White Wire Trigger Wiring

Diagram for wiring MSD to Ford DuraSpark systems using the White wire trigger.

FORD IGNITIONS WIRING (CONT.)

DuraSpark Magnetic Pickup Trigger Wiring

Diagram for wiring MSD to Ford DuraSpark systems using magnetic pickup trigger.

TFI System Wiring (Without Harness)

Diagram for wiring MSD to Ford TFI systems without using a dedicated harness.

FORD IGNITIONS WIRING (CONT.)

TFI System Wiring with Harness PN 8874

Diagram for wiring MSD to Ford TFI systems using the PN 8874 harness.

CHRYSLER IGNITIONS WIRING

Electronic Ignition (Magnetic Pickup)

Diagram for wiring MSD to Chrysler electronic ignition systems using magnetic pickup.

CHRYSLER IGNITIONS WIRING (CONT.)

Late Model Dodge (2-Pin Connector)

Diagram for wiring MSD to late model Dodge vehicles with a 2-pin connector.

Jeep Integrated Coil/Module Assembly Wiring

Diagram for wiring MSD to Jeep vehicles with integrated coil/module assemblies using PN 8813 kit.

HONDA IGNITIONS WIRING

Internal Coil Wiring

Diagram for wiring MSD to Honda vehicles with internal coils.

Blaster Coil and Power Cap Wiring

Diagram for wiring MSD to Honda vehicles using a Blaster Coil and Power Cap.

HONDA IGNITIONS WIRING (CONT.)

Factory External Coil Wiring (Honda/Acura)

Diagram for wiring MSD to Honda/Acura vehicles with factory external coils.

GENERAL IMPORT WIRING

AFTERMARKET COMPONENTS WIRING

Mallory Unilite/9000 Series (Points Trigger)

Diagram for wiring MSD to Mallory Unilite/9000 series distributors using points trigger.

Mallory 9000 Series (Magnetic Pickup)

Diagram for wiring MSD to Mallory 9000 series distributors using magnetic pickup.

AFTERMARKET COMPONENTS WIRING (CONT.)

Pertronix Ignitor Kit Wiring

Diagram for wiring MSD to Pertronix Ignitor kits.