MSD 85551 Chevy V8 Pro-Billet Distributor Installation - Manual

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Important: Read these instructions before attempting the installation.
Parts Included:
1 - Pro-Billet Distributor
1 - Rotor, PN 8467
1 - Distributor Cap, PN 8433
1 - Wire Retainer
2 - 1.5" Self Tapping Screws
2 - 10-32 x 3/4" Socket Head Screws
Note: The terminals of this Distributor require spark plug style terminals. You may need to change
the terminals and boots of your wires. MSD offers two kits, PN 8849 or PN 8848 that are supplied
with nine boots and terminals.
Note: If the gear is ever replaced, MSD Gear (PN 8531) is required for replacement due to the .500"
diameter shaft.
Note: A replacement Black cap is available as PN 84333.
TIMING FUNCTIONS
Before continuing with the installation, here are a few definitions you should be aware of:
Initial Timing: This is the base timing (also referred to as idle timing) of the engine before the
centrifugal advance begins.
Centrifugal Advance: The centrifugal (or mechanical) advance mechanism is made up of weights,
springs, advance cams, and an advance stop bushing. The amount and rate of advance that your
distributor is capable of is determined by the centrifugal timing. If you ever wish to lock out the
centrifugal advance, refer to the centrifugal advance section.
Total Timing: This is the total of the initial timing plus the centrifugal advance added together.
Example: 10° Initial + 25° centrifugal = 35° Total Timing. (When checking Total timing, disconnect
the vacuum canister and plug the vacuum source.)
Vacuum Advance (PN 8361 Only): The vacuum advance will advance the timing up to 10° during
partial throttle driving (with 15 in. lbs of vacuum). The vacuum line should be routed to a ported
vacuum outlet above the throttle plates.
Note: MSD Distributors are supplied with the heavy (slow) advance springs installed. This is to
prevent detonation in certain applications. Review the information on pages 2-4 to determine
the best advance curve for your application.
1 - Advance Kit
1 - Gasket
1 - Tube of Gear Lubricant
2 - O-Rings
1 - Vacuum Advance Lock-Out Kit
(PN 8361 Only)
WARNING: Before installing the MSD Distributor, disconnect the battery cables. When disconnect-
ing the battery cables, always remove the Negative (-) cable first and install it last.
MSD Pro-Billet Chevrolet V8 Distributor
PN 85551and PN 8589
with Vacuum Advance, PN 8361
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