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MSD Pro-Billet Dual Pickup Chevrolet
V8 Distributor
PN 8356
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
WARNING: Before installing the MSD Distributor, disconnect the battery cables. When
disconnecting the battery cables, always remove the Negative (-) cable
first and install it last.
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, an MSD Gear is required for replacement due to the .500" diameter
shaft. PN 8531 is iron, PN 8471 is bronze.
2 - 10-32 x 3/4" Socket Head Screws
1 - Advance Kit
1 - Gasket
1 - Tube of Gear Lubricant
2 - O-Rings
Note: An MSD Ignition Control must be used with each pickup.
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 c entrifugal advance added together.
Example: 10° Initial + 25° centrifugal = 35° Total Timing. (When checking Total timing, disconnect
the vacuum canister and plug the vacuum source.)
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.
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2 INSTALLATION INSTRUCTIONS
CHOOSING AN ADVANCE CURVE
The function of the advance curve is to match the ignition timing to the burning rate of the fuel and
speed (rpm) of the engine. Any factor that changes the burning rate of the fuel or the engine speed
can cause a need for an ignition timing change. Figure 1 shows some of the factors that will affect
engine timing.
FACTOR Advance Timing Retard Timing
For For
Cylinder Pressure Low High
Vacuum High Low
Energy of Ignition Low High
Fuel Octane High Low
Mixture (Air/Fuel) Rich Lean
Temperature Cool Hot
Combustion Chamber Shape Open Compact
Spark Plug Location Offset Center
Combustion Turbulence Low High
Load Light Heavy
Figure 1 Ignition Timing Factors.
As you can see from the chart, most factors will change throughout the range of the engine operation.
The timing mechanism of the distributor must make timing changes based on these factors.
Example: An engine has 11:1 compression with a high energy ignition. With the specifications given,
you will have to retard the timing for the high compression and high energy ignition. By comparing
the engine’s specifications against the chart, a usable timing guideline can be found. Engines with
a combination of items from both columns will require a timing that is set in the mid range.
Obviously a full technical explanation of correct ignition timing would be very complicated. The best
way to arrive at a suitable ignition curve for your engine is to use the Ignition Timing Factors Chart
as a guide and compare it to the Advance Graphs in Figure 4 until a suitable curve is found. When
selecting your advance curve, use detonation (engine ping) as an indicator of too much advance,
and a decrease in power as an indicator of too little advance.
TIPS ON SELECTING AN ADVANCE CURVE
• Use as much initial advance as possible without encountering excessive starter load.
• Start the centrifugal advance just above the idle rpm.
• The starting point of the centrifugal advance curve is controlled by the installed length and
tension of the spring.
• How quickly the centrifugal advance (slope) comes in is controlled by the spring stiffness. The
stiffer the spring, the slower the advance curve.
• The amount of advance is controlled by the advance bushing. The bigger the bushing, the smaller
the amount of advance.
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INSTALLATION INSTRUCTIONS 3
CENTRIFUGAL ADVANCE CURVE
SELECTING THE ADVANCE
SPRINGS
The rate, or how quick the advance comes in
is determined by the type of springs which are
installed on the distributor. The MSD distributors
are equipped with two Heavy Silver springs
installed. These will give you the slowest
advance curve possible (Figure 2). The parts
kit contains two additional sets of springs which
can b e used to match the advance curve to
your particular application. Refer to the Spring
Combination Chart (Figure 3) for combinations
that can be achieved.
To change the springs, remove the cap and
rotor and use needlenose pliers to remove the
springs. Be sure the new springs seat in the
groove on the pin.
Timing Curve From Factory
Figure 2 The Factory Equipped Curve.
SPRING COMBINATION RATE OF ADVANCE FIGURE 4
2- Heavy Silver SLOWEST A
1- Heavy Silver B
1- Light Blue
1-Heavy Silver C
1-Light Silver
2- Light Blue D
1- Light Silver E
1- Light Blue
2- Light Silver FASTEST F
Figure 3 Spring Combination Chart.
Figure 4 Advance Curves.
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4 INSTALLATION INSTRUCTIONS
SELECTING THE ADVANCE STOP BUSHING
Three different advance stop bushings are supplied
in t he distributor kit. The distributor comes with a
Blue (21°) bushing already installed. If a diffe rent
amount of centrifugal advance is desired, follow the
next procedure to change the bushings. The chart in
Figure 5 gives the size and approximate degrees for
the corresponding bushings.
CHANGING THE ADVANCE STOP
BUSHINGS
1. Remove the distributor cap and rotor.
2. Remove the locknut and washer on the bottom of
the advance assembly (Figure 6).
3. Remove the bushing and install the new one.
Install the washer and locknut. Do not o ver
tighten.
BUSHING SIZE APPROXIMATE
CRANKSHAFT
DEGREES
Red-Smallest 28
Silver 25
Blue 21
Black-Largest 18
Figure 5 Advance Stop Bushing Chart.
LOCKING OUT THE CENTRIFUGAL
ADVANCE
1. Remove the advance components including the
springs, weights and the advance stop bushing
from the advance assembly.
2. Remove the roll-pin from the drive gear and remove
the gear from the shaft.
3. Slide the shaft two inches out of the housing.
4. Rotate the shaft 180° and insert the advance stop
bushing pin into the small hole on the advance
plate (Figure 7).
5. Install the locknut and washer to the advance stop
bushing pin. This locks the advance in place. Do
not over tighten.
6. Install the drive gear and roll-pin.
Figure 6 Changing the Advance Stop Bushing.
Figure 6 Locking Out the Centrifugal Advance.
Figure 7 Locking Out the Advance.
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INSTALLATION INSTRUCTIONS 5
ADJUSTING THE SLIP COLLAR
Before installing the Pro-Billet Distributor, the slip collar adjustment must be set, follow this procedure.
1. Install the gasket on the housing then loosen the slip collar and insert the distributor into the engine
until it bottoms out against the oil pump drive.
2. After it bottoms out, raise the distributor 0.010" - 0.030" then slide the slip collar down into position
and tighten it.
CHECKING GEAR MESH
It is recommended to check for proper gear mesh between the cam gear and distributor gear. To
do this, coat the distributor gear with moly grease and install the distributor. Next, crank the engine
over several times. Before pulling the distributor out, make sure the rotor is in the position that lines
up with the original removal mark. Then pull the distributor out and inspect the gear pattern shown
on the grease. The proper mesh will leave an even pattern in the middle of the gear. Adjust the slip
collar to obtain the correct mesh.
Checking the Oil Pump to Distributor Shaft Overlap
The proper overlap between the distributor shaft and the oil pump shaft is very important. The tongue of
the distributor shaft should fit into the groove of the oil pump shaft by at least 1/4". To check this:
1. Measure the distance between the base of the slip collar to the tip of the distributor shaft (Figure
8).
2. Using a straight edge, measure the distance from the intake manifold distributor flange to the top
of the oil pump intermediate shaft (Figure 8).
3. Take the two measurements and subtract them. The difference is the overlap. There must be at
least 1/4" of overlap. If there is not enough clearance or too much clearance, a different oil pump
intermediate shaft is required.
Figure 8 Measuring Oil Pump Shaft Overlap.
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6 INSTALLATION INSTRUCTIONS
INSTALLING THE DISTRIBUTOR
1. Remove the existing distributor cap without
disconnecting any of the spark plug wires.
2. With the cap off, crank the engine until the
rotor is aimed at a fixed point on the engine or
firewall. Note this position by making a mark
(Figure 9).
3. Place the distributor cap back on and
note which plug wire the rotor is pointing
to. MARK THE SPARK PLUG WIRES and
remove the distributor cap.
4. D i s c o n n e c t t h e w i r i n g fr o m th e
distributor.
5. Loosen the distributor hold down clamp
and slide the clamp out of the way.
6. Lift the distributor out of the engine. Note
that the rotor rotates as you lift the distributor
out. This is due to the helical cut gear and
should be taken into consideration when
installing the new distributor.
7. Install the gasket and apply a liberal
amount of the supplied l ubricant to the
distributor gear. (The supplied O-rings
can only be used if the block has been
modified as shown in Figure 10.)
8. Install the distributor making sure that the
rotor comes to rest pointing at the fixed mark.
If the distributor will not fully seat with the rotor
pointing to the marked position, you may
need to rotate the oil pump shaft until the rotor
lines up and the distributor fully seats.
9. Position and tighten the hold down clamp
onto the distributor.
10. Install the distributor cap and spark plug wires
one at a time to ensure correct location. A
wire retainer is supplied to secure the wires
in place. Align the mounting bosses and use
the supplied 1.5" self-tapping Phillips screws
to hold the retainer in place.
Note: Block must be modified to use O-rings.
Figure 9 Marking the Rotor Location.
Figure 10 Modified Block for use with O-Rings.
Installation Option: This Cap can also be
bolted down to an MSD Pro-Billet or Billet
Distributor base with the supplied hardware.
To accomplish this, the spring clips must be
cut off (Figure 11).
Note: When the cap is bolted down, the
location of the spark plug wires must
be changed.
Figure 11 Optional Installation by Bolting Cap Down.
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INSTALLATION INSTRUCTIONS 7
DUAL
MAGNETIC
PICKUP
DISTRIBUTOR
TO DISTRIBUTOR
HARNESS PN 8860
AUTOMATIC COIL
SELECTOR
PN 8210
MAG
MAG
+
MAG
+
MAG
HARNESS PN 8860
(NOT USED)
ORANGE
BLACK
GRAY
TACH OUTPUT
RED
WHITE
GREEN (-)
VIOLET (+)
(NOT USED)
ORANGE
BLACK
MAGNETIC
PICKUP
GRAY
TACH OUTPUT
RED
WHITE
GREEN (-)
VIOLET (+)
SPDT SWITC
PN 8807
TO SWITCHED
12 VOLTS
MAGNETIC
PICKUP
DIGITAL 6AL
REV
LIMITER
DIGITAL 6AL
REV
LIMITER
Figure 12 Wiring with MSD 6TN, 6ALN, or 6-HVC Ignition Controls.
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Figure 13 Wiring with MSD 6A Series Ignition Controls.
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TECH NOTES
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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
MSD 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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© 2013 Autotr onic Contr ols Corpor ation
FRM29328 Revised 02/13 Printed in U.S.A.
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