Yellow Bullet Forums banner
1 - 4 of 4 Posts

·
Registered
Joined
·
33,118 Posts
The connection to the coil in the cap has three wires. The center wire is the ground for the coil secondary voltage. The center terminal in the cap must be grounded to the engine.

In the original HEI three-wire connector from the module to the coil, the center (black) wire grounds the coil to the screw that attaches the module harness to the distributor body.

The wires from the box to the coil (orange + and black – with MSD system, not sure on Mallory but your instructions have that info) are connected to the + (BATT) and – (TACH).

The center terminal in the cap must be grounded to the engine.

All the terminals must use insulated connectors because the ignition pulse from the box is high enough voltage to jump between them if they are not insulated. The probable reason you didn’t have spark is it was shorting between the terminals where the wires plug into the cap because the coil wasn’t grounded.


Don’t try to measure voltage on the wires from any CD box to the coil. The voltage pulse when the ignition fires will damage your voltmeter.

How are you triggering the CD box, the tan wire from the HEI module?
 

·
Registered
Joined
·
33,118 Posts
The “Orange” (actually probably faded pink or red) wire that originally went to coil + terminal connects to the small red wire in the Mallory harness and they both connect to the switched 12V power that turns on the system (ignition switch). That “orange” wire carries 12V to the module in the HEI to power it.

Brown wire from HEI module (originally went to the – coil terminal) connects to green (trigger) to CD box.

Connect the center coil terminal (originally connected to the HEI black wire) to the engine. That is the ground for the high-voltage to the spark plugs so ground it to the engine.

Do not connect the tachometer to the coil. Connect the tachometer to the “Tach” terminal on the CD box.
 

·
Registered
Joined
·
33,118 Posts
Do you have the orange and brown wires connected like this?:smt102
The “Orange” (actually probably faded pink or red) wire that originally went to coil + terminal connects to the small red wire in the Mallory harness and they both connect to the switched 12V power that turns on the system (ignition switch). That “orange” wire carries 12V to the module in the HEI to power it.

Brown wire from HEI module (originally went to the – coil terminal) connects to green (trigger) to CD box.

Connect the center coil terminal (originally connected to the HEI black wire) to the engine. That is the ground for the high-voltage to the spark plugs so ground it to the engine.

Do not connect the tachometer to the coil. Connect the tachometer to the “Tach” terminal on the CD box.
The (small) black and yellow wires from the Mallory box are the only wires to be connected to the coil. No other wires go to the coil.
 

·
Registered
Joined
·
33,118 Posts
Unless some other wiring problem is in play here, it sounds like the box is dead.

Is there 12V to the orange HEI wire and small red Mallory wire?

Follow the Mallory instructions to test the box.

Anyone else have any suggestions?
 
1 - 4 of 4 Posts
Top