67' 912-6 Conversion Charging Issue

[oldskool912]

Like the title says I swapped out the 1.6L 4cyl for a 2.1L 6cyl. I was given a 964 fan/alt and decided to go down that road because I like the look of the fan.

For starters battery voltage is 12.3V. Since I'm running an MSD I can watch the voltage drop slowly while the engine is running. Voltage does not change as I raise engine RPM's.

The charging light on the dash is not turning on when I turn the ignition to the "on" position. I confirmed 12V from the ignition switch at the charging light and I have grounded the D+ blue wire from the alternator to the charging light and the light does come on.

Since this is a 115 amp alt. I ran a 4ga "+" cable from the alt. to the starter terminal. I also ran a 4ga "-" cable from the alt. housing to a starter mounting bolt for a solid ground.

To confirm the chassis ground from the trans to the chassis is not the culprit I hooked up a temporary additional ground from the trans to chassis. Still not charging.

I have a new battery and I also replaced the alternator.

I feel there is a ground issue because with the alternator not tuning, the 12V from the D+ side of the alternator should be going to ground which should activate the charging light.

Is there something that I'm missing?
Thank you all for your help.

[john walker's workshop]

The blue D+/61 grounds through the brushes and when the engine is running, that ground becomes hot and the light goes out. Must not be grounding through the brushes.