REPLACEMENT CAP AND ROTOR

   This replacement cap and rotor is injection molded from Dupont Rynite material for high voltage isolation characteristics with heavy duty construction. Inside the cap there are thick vanes to help agitate the air to prevent the chance of crossfire. Stainless terminals are used for resistance to corrosion caused by ozone in the cap. The rotor is also molded out of Rynite and features a brass/stainless steel rotor tip plus has a lock screw for secure mounting to the Mag’s shaft.

Replacement 4" Cap and Rotor PN 7919

REPLACEMENT PRO MAG 44 CAP AND ROTOR

   This Cap and Rotor Kit is a replacement for the 44 Amp Pro Mags, or the 12 Amp Band Clamp models. The Cap is molded from alkyd material and has excellent high voltage isolation characteristics. Brass spark plug style terminals are used for solid connections and a firm grip to the plug wire terminal. The Rotor is injection molded from Dupont® Rynite™, strong glass reinforced material. Tall vanes are molded on the top of the rotor to stir up the air to prevent ozone build up and crossfire from occurring. A brass/stainless steel rotor tip is screwed into the rotor ensuring long life at high rpm.

Replacement Large Cap and Rotor PN 8119

Rotor Only PN 7920

REPLACEMENT BLACK RING

   Known simply as “the black ring” this is a replacement spacer that comes on full size band clamp Pro Mags (PN 8130, 8140, 8150, 8160 Generators)

Replacement Cap Ring PN 8120

CAP/WIRE RETAINER

   Racing produces high winds and severe vibrations which can actually “whip” a plug wire causing it to fall off. With an MSD Wire Retainer this is impossible! These Retainers will securely hold the Pro Mag’s cap in place while locking the spark plug wires to the terminals.

4" Cap PN 8113
Fits Tall Chevy Mags, PN 8139, 8149

Large Cap PN 8121
For Band Clamp Mount Pro Mags and the Cap-A-Dapt, PN 8123

CAP AND ROTOR OPTIONS

MSD’s Pro-Cap and Cap-A-Dapts increase the terminal-to-terminal distance to prevent chances of crossfire.

   MSD Pro Mags are engineered to fit a lot of different racing applications. Each Mag is supplied with a durable cap and rotor that has been tested for performance. When space permits, upgrading to a larger diameter magneto cap can further prevent chances of crossfire. Also, if you’re using a timing control to retard the timing, a Cap-A-Dapt is highly recommended because the retard affects the rotor phasing.

   By increasing the distance between the terminals, there is less chance of spark scatter as well as the build up of ozone inside the cap. MSD offers Cap-A-Dapts for all of the Pro Mags.

PRO CAP

SEEING IS BELIEVING
Below are two small videos showing how pickup timing can affect rotor phasing. These were made using a 44-amp system and the retard was changed from 0º to 28º. We used a standard cap that is supplied with all 44 amp generators and the new 6" diameter Pro Cap. Note that the Pro Cap has adjustment slots that can relocate the cap to compensate for timing changes. In the video clip with the Pro Cap, note the shorter distance between the rotor tip and cap terminal. We have also introduced an updated rotor tip. The new tip is wider and has a modified profile. Note the rounded edge on one side and the sharp corner on the other. Sharp points or corners tend to lower the voltage necessary to produce an arc between two surfaces. Placing the sharp edge on the trailing side of the tip ensures that the arc will always be sustained with the correct cap terminal and NOT jump ahead to the next cylinder (terminal).

900Kb	vs.	900Kb
Pro Cap		Ford Cap

New MPEG Footage shows some of the advantages the Pro Cap has over standard Ford cap. Click on the movie icons.

   To go with the huge power of the Pro Mag 44, MSD developed a huge cap and rotor, the Pro-Cap! The Cap has a big 5” terminal-to-terminal diameter which ensures spark delivery and prevents the chance of spark scatter occurring inside the cap. The entire assembly is injection molded from Dupont® Rynite™ material for incredible strength and high dielectric properties. The Rotor features a deep skirt and thick vanes to stir up the air and even the rotor screws are overmolded with Rynite for increased spark isolation. The top of the Pro-Cap is crowned with a screw-down retainer to keep all of the plug wires firmly attached to each terminal.

   The Pro Cap is supplied with everything you need to convert your Pro Mag 44 or band clamp mount 12 Amp Generator including an aluminum base, spacer, rotor, cap, retainer and hardware.

Pro-Cap for Band Clamp MSD Pro Mag PN 7455

INDIVIDUAL PARTS:
Wire Retainer	PN 7409
Rotor	PN 7423
Base	PN 7456
Cap	PN 7408

Old Style Rotor Blade	Old Style - Stainless Steel Ball	Old Style Terminals vs. New Wide Tip Terminals
New Rotor Blade	New Carbon Ball	New Adjustable Cap for Rotor Phasing

The Pro Cap measures 6" in outside diameter and comes with an adjustable base so rotor phasing can be optimized. More importantly, it also incorporates a newly designed "wide tip" rotor blade. Our first attempt at getting the big cap in the field, about a year and a half ago, didn't fare so well. We used a stainless steel rotor blade and cap terminals, along with a chrome steel ball in the center terminal. We have since changed the rotor blade to Nickel plated Copper, and the center terminal now incorporates a carbon ball. These changes were made as a result of feedback from teams that we test with. We've been running the new style ProCap since the beginning of the season and it seems like they're taking off.

ROTOR PHASING PRO CAP

   This cap features eight viewing holes that allow you to visually set the rotor phasing when using the Pro Cap kit.

Rotor Phasing Pro Cap PN 7405

12LT CAP-A-DAPT

   If space permits, this Cap-A-Dapt is a great update for Pro Mag 12LT generators. A billet aluminum housing bolts in place on the top of the mag, followed by an adapter ring. The rotor drive is modified to accept a larger rotor for the increased diameter of the new cap.

   The kit comes complete with a rotor adapter, rotor, cap spacer, housing and cap.

12LT Cap-A-Dapt PN 7460
Fits Generators, PN 7908, 7910, 7915, 7916 Only

Tall Chevy PN 8123
Fits Pro Mag PN 8139, 8149 Only