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INSTALLATION INSTRUCTIONS

Figure 1 Circle Track Ignition Controller, PN 6427

GENERAL INFORMATION

BATTERY

The Digital 6CT will operate on any negative ground, 12 volt electrical system with a distributor. The

unit can be used with 18 volt batteries and can withstand a momentary 20 volts in case of jump starts.

The ignition will deliver full output with a supply of 6 - 18 volts. If your application does not use an

alternator, allow at least 12 amp/hour for every half hour of operation. The MSD uses about .9 amps

for every 1,000 RPM. If the same battery is used to crank the engine and power other accessories,

such as an electric fuel or water pump, the battery amp/hour rating should be increased beyond the

12 amp-hour recommendation.

COILS

The Digital 6CT Ignition can be used with most stock coils and aftermarket coils designed to replace

the stock coils. For extended high RPM and race applications the Blaster HVC PN 8252, Blaster

HVC II PN 8253, or HVC Power Coil PN 8250, are recommended. For more information on MSD

recommended coils, check with our customer service department at (915) 855-7123.

TACHOMETERS

The 6CT features a gray tach output wire that provides a trigger signal for tachometers, a shift light

or other RPM activated devices. The Tach Output wire produces a 12 volt square wave signal with

a 20% duty cycle.

Some vehicles with factory tachometers may require a Tach Adapter to operate with the MSD. For

more information on tachometers and MSD Tach Adapters, see the tachometer section on page 9.

If your GM vehicle has an in-line filter it may cause the tach to drop to zero on acceleration. If this

occurs, bypass the filter.

SPARK PLUGS AND WIRES

Spark plug wires are very important to the proper operation of your ignition system. A good quality,

helically wound wire and proper routing are required to get the best performance from your ignition,

such as the MSD 8.5mm Super Conductor Wire. Helically wound wires provide a good path for the

spark to follow while keeping Electro Magnetic Interference (EMI) to a minimum. Excessive EMI, such

as the amount that solid core wires produce, will interfere with the operation of the MSD. Solid core

spark plug wires cannot be used with an MSD Ignition.