MSD 8680 Installation

Adjustable Timing Control

PN 8680

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IMPORTANT: Read the instructions before attempting installation.

Parts Included:

1 - Timing Control, PN 8680 1 - Control Knob 1 - 3/8" Bushing 1 - 2-Pin Weathertight Connector 4 - Self Tapping Screws

WARNING: During installation, disconnect the battery cables. When disconnecting the battery,

always remove the Negative cable ﬁrst and install it last.

Note: The MSD PN 8680 Timing Control must be used with an MSD Ignition Control. It is recommended

to install the MSD Ignition ﬁrst.

MOUNTING

The Timing Computer may be mounted in the engine compartment as long as it is away from direct engine heat sources. Make sure all of the wires reach their connections before mounting the unit. Use the Control as a template and mark the mounting holes. Remove the unit and drill the mounting holes using an 1/8" drill bit. Four self tapping screws are supplied to mount the unit. Note: Before mounting the unit, install the supplied grommets and sleeves as shown in Figure 1.

PROGRAMMING

The Timing Control is programmed for 8-cylinder. If installing the PN 8680 on a 4 or 6-cylinder, the Control must be programmed. Locate the Cylinder Select cover on the side of the unit and remove the single Phillips screw (Figure 2).

CYLINDERS CUT LOOPS

Number of Cylinders: The Red loop and the Blue loop are responsible for cylinder programming. The chart in Figure 2 shows which loop(s) to cut.

8 NONE 6 RED 4 RED AND BLUE

Note: After cutting a loop, position the wire ends

away from each other so they cannot make contact.

Figure 2 Selecting the Number of Cylinders.

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Figure 1 Installing the

Vibration Mounts.

2 INSTALLATION INSTRUCTIONS

WIRING

Figure 3 How to use the Supplied Wire Splice Device.

WIRE FUNCTIONS

Yellow This is the trigger output wire. It connects to the White wire of an MSD 6 Series Ignition or

“Points” terminal of a 7 Series Ignition.

Red This wire is responsible for turning the Timing Control on and off. It connects to switched

12 volt source. It can be spliced into the small red wire of the MSD.

Black This is the ground wire and must be connected to a good engine or chassis ground.

TRIGGER WIRES

Violet These wires connect to the magnetic pickup of the distributor or crank trigger. The Green Violet is positive (+) and the Green wire is negative (-). When this connector is used

the White wire is not. White This is the trigger input wire for breaker points or ignition ampliﬁer. When this wire is used,

the magnetic pickup wires (violet and green) are not.

Control Knob

The Black and Gray wires with the 2-Pin Weathertight connector are the Control Knob wires. After the Timing Control is mounted, the Harness should be routed to the unit. The Control Knob should be mounted within easy reach of the driver. Before mounting the Control Knob, make sure the wiring harness reaches the unit. If the harness must be routed through the ﬁrewall, drill a 3/8" hole and use the supplied grommet to route the wires through. Install the supplied 2-Pin Weathertight connector to the wires after all of the routing is ﬁnished (Figure 4). The position of the wires in the connector is not important.

Figure 4 Installing the Weathertight Connector.

Operating the Control

After installation, it is recommended to check the timing. Before starting the vehicle, turn the Control Knob to the full 15° mark. This is the stock timing setting. As the Knob is turned counterclockwise, the timing retards. As detonation occurs, slowy retard the timing until the “pinging” noise is not audible. Adjust the timing as driving conditions change.

Resetting the Timing

It is possible to set the Timing Control up to where you can retard and advance the timing 7.5° each. To do this, position the Control Knob in the center (approximately 7.5°) then reset the timing to factory speciﬁcations.

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BLACK

WHITE

RED

YELLOW

FROM IGNITION

KEY

INDICATES CONNECTION USING

WIRE SPLICE DEVICE

TO GROUND

ORANGE

MAG PICKUP

NOT USED

TIMING

CONTROL UNIT

TACH

OUTPUT

IGNITION

Multiple

Spark

Discharge

MSD

COIL

C+

C-

POINTS

OR AMPLIFIER

DISTRIBUTOR

ORIGINAL

COIL WIRE

ORIGINAL COIL+ WIRE

HEAVY RED

HEAVY BLACK

TO BATTERY+

TO BATTERY-

TIMING

CONTROL

MAG PICKUP

INSTALLATION INSTRUCTIONS 3

DIAGRAMS

The following wiring diagrams show common installations.

NOTE: The MSD 5 and Blaster Ignitions are inductive designs and do not share the same wiring as the 6-Series Ignitions.

Figure 5 Wiring to a Points or Ampliﬁer Ignition with an MSD 5 or Blaster Ignition using the Points Trigger.

ORIGINAL COIL+ WIRE

FROM IGNITION

KEY

BLACK

ORANGE

HEAVY RED

HEAVY BLACK

RED

TO BATTERY+

TO BATTERY-

GRAY

DIGITAL 6A

TACH OUTPUT

POINTS

OR AMPLIFIER

DISTRIBUTOR

WHITE

GREEN (-)

ORIGINAL

COIL WIRE

RED

YELLOW

VIOLET (+)

MAG PICKUP

MAGNETIC PICKUP

BLACK

TO GROUND

(NOT USED)

NOT USED

WHITE

INDICATES CONNECTION USING

WIRE SPLICE DEVICE

TIMING

CONTROL

TIMING

CONTROL UNIT

Figure 6 Wiring to Points or Ampliﬁer Ignition with an MSD 6 Series.

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4 INSTALLATION INSTRUCTIONS

The PN 8680 can be installed with other magnetic distributors. The polarity of the pick-up wires must be correctly wired to the MSD.

RED

ORANGE

WHITE

BLACK

VIOLET (+)

MAGNETIC PICKUP

GREEN (-)

(NOT USED)

Figure 6 Wiring to Magnetic Pickup Trigger with an MSD 6 Series.

CGND B+

18” BLACK TO

ENGINE GROUND

YELLOW

GREEN (-)

VIOLET (+)

MAGNETIC PICKUP

(NOT USED)

DIGITAL 6A

GRAY

TACH OUTPUT

MAGNETIC PICKUP

(NOT USED)

GRAY

BLACK

TO GROUND

DIGITAL 6A

TACH OUTPUT

TIMING

CONTROL

TIMING

CONTROL UNIT

Figure 7 Installation to a GM HEI with a 5 or 7-Pin Module (Points Trigger).

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INSTALLATION INSTRUCTIONS 5

CGND B+

DIGITAL 6A

18” BLACK TO

ENGINE GROUND

RED

GREEN (-)

VIOLET (+)

TACH OUTPUT

GRAY

MAGNETIC PICKUP

(NOT USED)

WHITE

(NOT USED)

YELLOW WHITE

YELLOW

RED

Figure 8 Installation to a GM HEI with a 4-Pin Module (Magnetic Trigger).

Note: The PN 8876 and PN 8877 Harnesses install the same as the 8874 shown.

MAGNETIC PICKUP

BLACK TO GROUND

(NOT USED)

TIMING

CONTROL

GRAY

GREEN (-)

VIOLET (+)

DIGITAL 6A

TACH OUTPUT

MAGNETIC PICKUP

(NOT USED)

TIMING

CONTROL UNIT

Figure 9 Wiring with an MSD PN 8874, 8876 or 8877 Harness.

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6 INSTALLATION INSTRUCTIONS

Note: The MSD 6 and 7 Series Ignitions share the same wire colors.

ORANGE

BLACK

ORANGE

BLACK

Figure 10 Wiring to Points or Ampliﬁer with an MSD 7 Series.

Figure 11 Wiring to Magnetic Pickup with an MSD 7 Series.

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INSTALLATION INSTRUCTIONS 7

DIGITAL 6A

TACH OUTPUT

GRAY

MAGNETIC PICKUP

(NOT USED)

TIMING

CONTROL UNIT

BLACK

TO GROUND

TIMING

CONTROL

GREEN (-)

VIOLET (+)

MAGNETIC PICKUP

(NOT USED)

Figure 12 Wiring to a Mallory 3-Wire Distributor.

TACH OUTPUT

GRAY

MAGNETIC PICKUP

(NOT USED)

CONTROL UNIT

DIGITAL 6A

TIMING

GREEN (-)

VIOLET (+)

BLACK

TO GROUND

MAGNETIC PICKUP

(NOT USED)

TIMING

CONTROL

Figure 13 Wiring to a Mallory Distributor w/ Mag Pickup.

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TECH NOTES

_________________________________________________________________________________________________________________________

Service

In case of malfunction, this MSD component will be repaired free of charge according to the terms of the warranty.

When returning MSD components for warranty service, Proof of Purchase must be supplied for veriﬁcation. After the warranty period has expired, repair service is based on a minimum and maximum fee.

All returns must have a Return Material Authorization (RMA) number issued to them before

being returned. To obtain an RMA number please contact MSD Customer Service at 1 (888) MSD-7859 or visit our website at www.msdperformance.com/rma to automatically obtain a number and shipping information.

When returning the unit for repair, leave all wires at the length in which you have them installed. Be sure to include a detailed account of any problems experienced, and what components and accessories are installed on the vehicle. The repaired unit will be returned as soon as possible using Ground shipping methods (ground shipping is covered by warranty). For more information, call MSD at (915) 855-7123. MSD technicians are available from 7:00 a.m. to 5:00 p.m. Monday - Friday (mountain time).

Limited Warranty

SD warrants this product to be free from defects in material and workmanship under its intended normal use*, when properly installed and purchased from an authorized MSD dealer, for a period of one year from the date of the original purchase. This warranty is void for any products purchased through auction websites. If found to be defective as mentioned above, it will be repaired or replaced at the option of MSD. Any item that is covered under this warranty will be returned free of charge using Ground shipping methods. This shall constitute the sole remedy of the purchaser and the sole liability of MSD. To the extent permitted by law, the foregoing is exclusive and in lieu of all other warranties or representation whether expressed or implied, including any implied warranty of merchantability or ﬁtness. In no event shall MSD or its suppliers be liable for special or consequential damages. *Intended normal use means that this item is being used as was originally intended and for the original application as sold by MSD. Any modiﬁcations to this item or if it is used on an application other than what MSD markets the product, the warranty will be void. It is the sole responsibility of the customer to determine that this item will work for the application they are intending. MSD will accept no liability for custom applications.

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FRM28680 Revised 05/12 Printed in U.S.A.

MSD 8680 Installation

Specifications and Main Features

Frequently Asked Questions

User Manual