68-69 factory tach wiring with MSD ignition and Tach Adapter

[momoparman]

I am trying to figure out which terminal is which on my factory 6000rpm tach.

I have what looks like a long threaded post and a short threaded post on the back of the factory tach.

I am using an MSD ignition with the tach adapter and one wire is supposed to tie into the factory tach input terminal and the other provides 12 volts to the tach if needed.

Does anyone know which post is which or if I need to feed 12 volts to the tach at all? The tach is installed so I can't see anything markings on the back I can only see the 2 posts.

Thanks

Mop

 

[momoparman]

Bump...anyone know or have pics of the back of the tach?

 

[momoparman]

I'm kinda shocked that nobody knows.........it can't be that elusive.

Tall post = voltage or signal from coil negative?

Short post = voltage or signal from coil negative?

I hate to hook it up backwards and burn it up.....HELP.

 

[67Dart273]

Orange--dash lamp

Black--ground

Violet--switched 12V

Green--to neg. side of coil

According to this:

http://www.forabodiesonly.com/mopar/showthread.php?p=1969893876

and this

http://www.forabodiesonly.com/mopar/attachment.php?attachmentid=1714601847&d=1363325975

the long stud is 12V, short stud is tach trigger

 

[momoparman]

Awesome....I was getting impatient and about ready to possibly make a mistake so I appreciate the help. rayer:

Mop

 

[momoparman]

Worked like a charm....tach is up and running.

Thanks for the help.