MSD 8985 Installation

MSD Timing Tapes

PN 8985

Important: Read the instructions before attempting the installation.

Parts Included:

1 - Timing tape sheet (8 tapes)

Note: The MSD Timing Tapes are used so you can accurately set your initial and total timing when

you don’t have a fully degreed balancer. This is crucial for optimum engine performance.

TIMING FUNCTIONS:

One timing setting is not optimum throughout the different rpm range of the engine. The centrifugal,
or mechanical, advance of the distributor alters the timing to match the changing rpm. This is
achieved through centrifugal force and can be tuned to match the specifications of your engine.

Initial Timing: This is the base timing (also referred to as idle timing) of the engine before the
centrifugal advance begins. This is where the timing is set by rotating the distributor in the engine.

Centrifugal Advance:

On MSD distributors, the advance mechanism is made up of weights, springs,
and advance cam bushings. The centrifugal, or mechanical, advances the timing to match the
requirements of the engine as RPM increases. Most other distributors have similar setups. The amount
and rate of advance that your distributor is capable of is determined by the centrifugal timing.

Total Timing: This is the total of the initial plus the centrifugal advance added together. Example:
10 degrees initial + 25 degrees centrifugal = 35 degrees total timing.

Vacuum Advance: The vacuum advance will advance the timing during partial throttle driving. The
amount will vary depending on the type of distributor you’re using. MSD distributors will advance
the timing up to 16 degrees. This should be disconnected when you’re setting the timing.

40°

30°

20°

Degrees

10°

0

1000

2000

3000

4000

RPM

5000 6000

Initial

Timing

Centrifugal

Timing

Total

Timing

Figure 1 Typical Timing Curve.

MSD IGNITION • 1490 HENRY BRENNAN DR., EL PASO, TEXAS 79936 • [phone] • FAX [phone]

INSTALLATION

1. Locate the top-dead center or “0” degree mark on the

harmonic balancer or timing wheel.

2. Select the correct timing tape for your application. Make

sure you know the correct size of the harmonic balancer
or timing wheel you’re using. If this is not known,
measure the diameter of the harmonic balancer or timing
wheel’s edge and note the size.

3. Choose the timing tape that matches your balancer’s

diameter. Be sure that the mating surface is clean of any
dirt, grease or debris. Locate and note the “0” degree
mark on the timing tape.

4. Align the 0 degree mark on the tape with the TDC mark

on the balancer. Make sure that the markings on the
tape are facing you, and place the tape on the surface.
Use firm pressure for proper adhesion. ATC (after top­dead center) will be to the left of the stock mark, and
BTC (before top-dead center) will always be to the right
of the stock mark.

Figure

2 The Timing Tape Installed.

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 service, Proof of Purchase must be supplied for warranty
verification. After the warranty period has expired, repair service is charged based on a minimum and
maximum charge.

Send the unit prepaid with proof of purchase to the attention of: Customer Service Department, MSD
Ignition, 12120 Esther Lama, Suite 114, El Paso, Texas 79936.

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 after receipt, COD for any charges. (Ground
shipping is covered by warranty). All units are returned regular UPS unless otherwise noted. For more
information, call the MSD Customer Service Line [phone]. MSD technicians are available from 8:00
a.m. to 5:00 p.m. Monday - Friday (mountain time).

Limited Warranty

MSD IGNITION warrants MSD Ignition products to be free from defects in material and workmanship
under normal use and if properly installed for a period of one year from date of purchase. If found to be
defective as mentioned above, it will be replaced or repaired if returned prepaid along with proof of date
of purchase. This shall constitute the sole remedy of the purchaser and the sole liability of MSD Ignition. To
the extent permitted by law, the foregoing is exclusive and in lieu of all other warranties or representations
whether expressed or implied, including any implied warranty of merchantability or fitness. In no event
shall MSD Ignition be liable for special or consequential damages.

MSD IGNITION • 1490 HENRY BRENNAN DR., EL PASO, TEXAS 79936 • [phone] • FAX [phone]

FRM 26221 Created 08/04 Printed In U.S.A.