Another MSD 6AL Problem

[Jack21]

The white wire is used with a points type ignition for making and breaking the circuit. The spark is made when the white wire becomes ungrounded (points just opening).

White wire is not used for mag pickup ignition except for diagnostics. You can disconnect the mag pickup, and tap the white wire on a ground, and get spark from the coil.

The coil wires are polarized (+, & -), because the coil is polarized; + to the plugs, - to the block. (The engine may, or may not run with this backwards, but not very well.)

A conventional ignition runs 12 volts to the coil during start, and about 7 volts from the ballast resistor when the engine is running. A capacitor discharge (CD), be it MSD, Accel, Crane, or any of the others out there work by sending a pulse of about 480 volts to the coil. Several of these pulses are sent to the coil with the MSD multiple spark feature. These pulses, generated when the charged capacitor discharges, generate the spark in the coil. Most CD system coils cannot be used with a conventional ignition because the windings are different. (Although CD coils are interchangable. Accel, and Crane PS91 work fine with MSD.)

Anyway, my guess is that the MSD is damaged, or defective to start with. Get an RMA from MSD, and send it back to MSD Tech for an eval and repair or replacement.