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Discussion Starter #1
I installed my MSD 6A and hooked it up to my Autogage tach. No workee. Instructions say to purchase a MSD Tach Adapter 8920 (for Autogage). Upon reading the instructions it appears that my Autogage is a voltage triggered tach (tach trigger wire to neg. - on coil). I have everything hooked up according to the instructions and still no workee! Any ideas? Anything I can test to make sure the adapter is working. I'm no electrical whiz but I know enough basics to get by. When I hit the key the tach needle makes a slight movement? Tach did work before the MSD 6A.

Thanks for any help. I know MSD has a tech forum but to search a topic as I word it might be difficult.
 

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I had the same problem... search under MSD or my name and you'll find an old post about it.
I recall I had to run a 12V dedicated line instead of the switched 12V that MSD required.
 

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Which wire are you using to trigger the box?

From mds forum (which by the way is a joke imo)

Use PN 8910 iof you're using the white wire to trigger the MSD, or PN 8920 if you're using the green and violet wires to trigger the MSD.
 

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Discussion Starter #6
I am triggering my MDS Pro Billet FE distributor with the viotet/green wire connector. This indicates the need for the 8920.

6A box wiring:
Heavy red - to solenoid
Heavy black - to engine block
skinny red - to original 12V feed to poistive side of original coil
violet/green - Distributor
Orange/black - to coil
White - not used, end taped off

8920 adapter:
White - to tach out put on MSD 6A
Black - grounded to inner fender apron
violet - to trigger wire on tach (originally to neg. - on coil)
red - to stud on back of ignition switch

Thats the wiring.
 
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