MSD 7455 Installation Instructions

Pro Cap for the MSD Pro Mag
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Parts Included:
1 – Pro Cap, PN 7408
1 – Adapter Ring
1 – Rotor, PN 7423
1 – Rounded Rotor Tip
2 – O-Rings
This Cap is designed to be used with MSD Pro Mags that are equipped with a Ford style cap (4"
terminal diameter) and rotor. If you have a Pro Mag 12 that has the small diameter distributor cap on
it, the unit must be sent to MSD to be modified to accept a Pro Cap.
Note: Blue Loctite or an equivalent thread locking compound is recommended for this installation.
ROTOR TIP INSTALLATION
A modified Rotor Tip is supplied with the Pro Cap Kit, PN 7455, and the Pro Cap Rotor, PN 7423.
This Rotor Tip must be used when the ignition timing of the Pro Mag is being retarded. The modified
Rotor Tip has a 90° corner on one side and a rounded edge on the opposite side. Installation of the
Tip depends on the rotation of the Pro Mag. The rounded edge of the rotor must point in the direction
of the mag's rotation (the rounded edge is always the leading side). Note that there is also an arrow
designating the rotation stamped on both sides of the new Tip.
The reason for this modification is because voltage will travel to and from the sharpest point of the rotor tip.
By rounding the leading edge of the Tip, the voltage will jump from the sharp point (trailing edge) of the tip
which will be closer to the spark plug wire terminal when the timing is retarded. This will produce proper
spark distribution even when the timing is retarded (which alters the rotor phasing).
The Figures show the Rotor Tip installation.
CCW
ROTATION
M S D
• w w w . m s d P E R F O R m A N C E . C O m • ( 9 1 5 ) 8 5 5 - 7 1 2 3 • F A X ( 9 1 5 ) 8 5 7 - 3 3 4 4
PN 7455
2 – Plastic Hex Head Rotor Screws
4 – 8-32 x 1.25 Socket Head Cap Screws
4 – 10-32 x 1.25 Pan Phillips Screws
1 – Billet Housing
1 – Wire Retainer
CCW
ROTATION
Figure 1 Installing the Rotor Tip.
4 – Self Tapping Screws
3 – Truss Head Phillips Screws
8 – Belleville Washers
3 – Stainless Washers
CW
ROTATION
CW
ROTATION