MSD 8423 Fixed Rotor Installation User Manual
Msd rotor, pn 8423

WARNING: Disconnect the battery during installation. When disconnecting the battery, always
remove the negative cable first and install it last.
Figure 2 Washer Installation.
MSD Rotor, PN 8423
Fits MSD Cap-A-Dapt, PN 8445 and PN 8441
also, MSD Distributors with Cap PN 8408
Parts Included:
1 – Rotor, PN 8423
2 – 5/8” Phillips Head Screws
IMPORTANT: There are two different length screws supplied with this rotor. It is important to determine
which screws are correct for your application due to clearance of the magnetic pickup.
Remove the cap, rotor and the cap spacer and note the rotor screw retainer that is installed on the bottom
of the advance plate (Figure 1). There are two styles used; one is a Screw Retainer, the other is a Retainer
with a Nut. The Retainer accepts the shorter 5/8” screw while the Nut version accepts the ¾” screw.
Once the rotor screw length is determined, install the rotor being
sure the round and square aligning pegs are lined up correctly.
Install the Belleville washers with the
dome facing up on the screws
and tighten the rotor (Figure 2). Install the cap and plug wires.
Figure 1 Determining Rotor Screw Length.
Note: It is recommended to install the rotor and check the clearance
before reassembling the distributor.
ROTOR SCREW
RETAINER
ROTOR SCREW
RETAINING NUT
USE 5/8"
SCREW
USE 3/4"
SCREW
2 – 3/4” Phillips Head Screws
2 – Belleville Washers
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