Original Tachometer installation??

[colocolino]

Ok so i purchased a tachometer from charger specialties a while back and I am just now getting around to installing it. I have found several threads about installing the tach and it seems pretty simple except that there seems to be two different ways to hook up the wiring. Both say to hook up the ignition wire to a 12v source which i have done so. The problem i am encountering is deciding where to connect the second wire. Some say to connect to the negative terminal on the coil, which i have tried to no avail and the others say to connect to the main wire on the coil that directly feeds the distributor. So i was about to do that but i wanted to double check with the experts to make sure thats what i should do. Im a little worried about hooking up the tach to a connection that puts out such high voltage. Can anyone clarify for me?? I have included some pics to visualize my dilemma. THanks a Bunch!!

[colocolino]

Here's a second pic of where Im thinking about connecting the other wire. is this right??

[y3chargerrt]

NOOOOOOOOOOOOOOOO!! Connect the second lead to the negative of the coil.  You WILL be buying a new tach if you connect it to the output of the coil. Might be cool to watch though..

[colocolino]

HMMM but i have done that and i got no read on the tach. I know im getting 12 volts, could it be the tach thats not working?? is there a way to test it before assuming thats the problem?

[y3chargerrt]

Connect the lead labeled tach to the negative of the coil. Also make sure the leads dont ground to the case of the tach. If it still doesnt work you probably fried the tach..sorry

[2Gunz]

If you hooked it up like in the picture....... Shes dead jim.

[BROCK]

Crank the car, make certain that you are getting 12V to the hot side of the
Tach & that the other side is on the NEG of the coil.  If still nothing it = bad
tach.  It is my hope that you just aren't getting 12V to the hot side of the
Tach.

[colocolino]

No! I definitely have not hooked it up to what you see in the pic... I added that just to give a visual as to where I was Thinking about connecting it to based of some information I had read  . I will give it another shot manana connecting it to the negative on the coil and double checking the 12v source. Thanks again everyone!

[lisiecki1]

I have never seen a tach that had a positive feed and tach feed and no ground....maybe you're supposed to ground the case of the tach to complete your power circuit to power up the tach.  That would probably be your safest option to try.

BTW, your 12v source isn't the positive side of the coil is it?  You need clean constant direct 12v power.


Randy


**edit...after looking at your picture again I can see a copper ground strip attached to the tach for a light, which leads me to believe that the tach needs to be installed to be grounded appropriately or it will not function.

[Nacho-RT74]

the others say to connect to the main wire on the coil that directly feeds the distributor.

WHERE IN THE WORLD DID YOU READ THAT ?

ONLY diff location than the negative side of coil is when you use MSD ( or similar ) ignition system, where MSD provides the source on box and needs a translator/adaptor to use old tachs unable to read multispark systems.

[colocolino]

lisiecki1 you were on the money! All i had to do was ground it and its working great  Thanks everyone for the input... now i can get back to setting the timing.

[y3chargerrt]

Glad you didn't fry your tach!

[lisiecki1]

lisiecki1 you were on the money! All i had to do was ground it and its working great  Thanks everyone for the input... now i can get back to setting the timing.

glad to help my friend!

[71charger_fan]

I just ordered a Charger Specialties tach for my '71. Do you have a photo of the dash after the install?