So I just installed a new pillar tach as the stocks are so off. I got everything wired up fine and it was reading like it should, drove about 2 miles from the house on a test run and the car died. Pulled over to the side of the road and checked what what wrong. Dizzy was making noise so I pulled the cap to the coil and was met with a face full of smoke and a coil that was melting from the inside and oozing out.

What did I do wrong or what could have happened?

 

I should also note that the positive line was wired to a constant power switch rather than an ignition power switch for testing purposes only and would be put to ignition when I knew it all worked. Any help would be great as I will be going for round 2 on the tach once the coil is replaced.

 

Alright I've been up all night trying to find an answer to this and I just read that if the tach wire grounds out at all it can fry the whole thing, coil and ICM, I was careful not to ground it out anywhere, but I guess one can never be too careful Thinking back, the splice connection on the wire may have had its flimsy plastic cover lose and the metal may have been exposed. My coil and ICM should be covered under warranty and so hopefully this won't be a painful goof.

 

So I was just paranoid, the coil was faulty and it fried the ICM too, but will be replacing the whole distributor anyways and going with a non CC HEI instead to fix it. I know no one responded but in case anyone has the same problem later, it may be caused by the tach grounding but in my case I had the weirdest coincidence and that was it.