MSD 8985 Timing Tapes for Harmonic Balancers Installation - Manual

MSD IGNITION • 1490 HENRY BRENNAN DR., EL PASO, TEXAS 79936 • (915) 857-5200 • FAX (915) 857-3344
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.
1000 2000 3000
RPM
Centrifugal
Timing
Initial
Timing
Degr
ees
Total
Timing
4000 5000 6000 0
10°
20°
30°
40°
Figure 1 Typical Timing Curve.