Wiring Tachometers

[fasttback]

In my ’66 I have installed the original tach wiring available from many Mustang part dealers. I’ve noticed it utilizes the positive side of the coil. My aftermarket tach requries the negative side of the coil. Are there any tachs out there that use the positive side (besides the original ones)? Also I by-passed the resistance wire some time ago, so 12V flows through the circut.

I'm in the process of wiring to the neg side of the coil for the current tach, but I hate adding more and more unmarked wiring to the system. Options?

 

[Rusty67]

If you aren't going to use the old tach then just use the existing wire and move it to the other terminal on the coil.

 

[fasttback]

If you aren't going to use the old tach then just use the existing wire and move it to the other terminal on the coil.

Thanks Rusty. Obvious answer, but overlooked by me...many times. I don't know where my brain was during the wire installation!!!!

 

[Rusty67]

Haha, no problem. When yer looking into wiring sometimes its like looking into a bowl of spaghetti. Thats what stangnet is here for. Don't feel bad about it, I miss the obvious answers all the time too =)

 

[fasttback]

Well looks like I really need to learn electronics - switching from the positive to negative terminal on the coil burned out my Mallory module with a click of the ignition.

After backtracking and checking all ignition connections for voltage and coil issues, my worst fear came true. Switching out my distributor for an older Mallory Unilite I had solved the problem. LESSON LEARNED!

 

[Rusty67]

Interesting... did you get the tach working ? Can you send me a link to the tach you bough or maybe a link to the instructions ?

 

[fasttback]

Interesting... did you get the tach working ? Can you send me a link to the tach you bough or maybe a link to the instructions ?

Yes, after switching the 12V connection back to the positive side of the coil and replacing the distributor everything is working. Since the original idea did not work, I have two dedicated lines for the new tach (just more wiring - something I was trying to advoid).

The tach is a rather cheap one, but I had it lying around. I will try to get the instructions posted after work.