MSD 84111 HEI Extreme Cap and Rotor Kit includes Installation User Manual

Msd extreme hei cap

background image

MSD Extreme HEI Cap

PN 84111

10-14 x .750


Parts Included In This Kit

1 - PN 84111, MSD HEI Cap

1 - Factory Rotor Bushing

1 - Low Resistance Rotor Bushing, PN 8412

1 - Insulator

This cap is supplied with a stock GM rotor bushing as

well as an MSD Low Resistance Bushing, PN 8412, which

only has 1 - 3 ohms. The Rotor Bushings used in GM

HEI Distributors are made from high resistance carbon

to help suppress radio frequency interference. However,

when the increased voltage and spark energy of an MSD

Ignition Control is added, this high resistance may build

up excessive heat which may damage the cap or rotor.

The Low Resistance Bushing allows the secondary

voltage to be transferred from the cap to the rotor without

excessive heat build up. The stock bushing is black with

a bronze tip while the Low Resistance Bushing is solid


Stock HEI or a Performance Coil: It is recommended

to use the Stock Rotor Bushing in stock applications.

The higher resistance reduces the chance of excessive

Electro Magnetic Interference, or radio noise. If you

have only added a performance coil, use this Bushing

as well.

MSD 6A Series Ignitions: GM used a variety of Rotor

Bushings with a large variance in resistance and in

most cases with a 6 Series Ignition, the Low Resistance

Bushing is not required. In applications where the engine

will be running at high rpm for long amounts of time, it is

recommended to use. If you experience any problems

within your cap and rotor, install the PN 8412.

MSD Digital Ignitions and 7 Series Ignitions: The Low

Resistance Bushing is required.

Note: The MSD Pro-Billet HEI Distributor, PN 8365, is

supplied with the Low Resistance Bushing.

1 - Extreme Coil Cover, PN 84022

3 - 10-14 x .750 Screws

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 7 - 5 2 0 0   •   F A X   ( 9 1 5 )   8 5 7 - 3 3 4 4

© 2012 Autotronic Controls Corporation


Revised 12/11

Printed in U.S.A.