MSD 8489 Installation

MSD Billet Crank Trigger Distributors

PN 8489 and PN 8486

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Note: Read these instructions completely before attempting the installation.

Parts Included:

1 - MSD Distributor Assembly 2 - O-Rings 1 - Tube of Gear Lubricant

Replacement Parts:

Rotor, PN 8567 Rotor Base, PN 8568 Crab Cap, PN 8541 Standard Bronze Gear (0.500" ID), PN 8471 Oversize (0.006") Bronze Gear (0.500" ID), PN 8472

WARNING: During installation, disconnect the battery cables. When disconnecting the cables, always remove the Negative cable ﬁrst and install it last.

Note: A Crank Trigger must be used with this distributor. An MSD Billet Hold-Down Clamp, PN 8110, is recommended.

O-RING SEALS

The MSD Billet Distributor features two O-ring grooves in the bottom lands of the housing to seal the oil gallery. These O-rings should only be installed if the block has been modiﬁed as shown in Figure 1.

NOTE: BLOCK MUST BE MODIFIED TO USE O-RINGS.

Figure 1 Modiﬁed Block to Accept the O-Ring Seals.

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2 INSTALLATION INSTRUCTIONS

REMOVING THE DISTRIBUTOR

1. Remove the existing distributor cap without disconnecting any of the spark plug wires.

2. With the cap off, rotate the engine or until the rotor is aimed at a ﬁxed point on the engine or ﬁrewall. Note this position by making a mark (Figure 2).

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. Loosen the distributor hold-down clamp and slide the clamp out of the way.

5. 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 a new distributor.

Figure 2 Marking the Rotor Location.

PREPARING THE DISTRIBUTOR

The MSD Billet Distributor features an adjustable slip collar. This collar provides an adjustment to accomodate variations in block height, modiﬁed intakes or heads. It is recommended to check the slip collar setting before installation. MSD offers a special tool, the 3-In-1 Distributor Set Up Tool, PN 8599, to make these adjustments accurately. If the tool is not available, follow this procedure.

ADJUSTING THE SLIP COLLAR

1. 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 the position and tighten it.

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:

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.

1. Measure the distance between the base of the slip collar to the tip of the distributor shaft (Figure 3).

2. Using a straight edge, measure the dis tan ce fro m the in tak e manifo ld distributor ﬂange to the top of the oil pump intermediate shaft (Figure 3).

3. Take the two measurements and subtract them. The difference is the overlap. If there is not enough clearance or too much clearance, a different oil pump shaft is required.

Figure 3 Checking Oil Pump Shaft to the

Distributor Shaft Overlay.

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