Ignition coil / Tach hookup

[Grundy]

The car is 99% rewired, totally new harness, the whole bit. Now, I just want to be clear on the ignition wiring. I don't have any problems on the "+" side. I've got the ballast resistor in there, etc. My question is, when hooking up the negative to the tach, should that negative on the coil also be grounded? When i got the car, the tach was dead and disconnected. The negative side of the coil was grounded to the block. NOw, I installed the new tach kit from RT engineering, put it all back together, and I want to make sure the hookup is correct. I don't want to fry new gauges. Tonight we fire it up!! IT's been about 6 months since it ran. I can't wait.

[ted]

DOESNT grounding the negative terminal result in a no spark condition?

[Grundy]

It was hooked up that way before I redid the electrical, and it definitely ran.

[MEK-Dangerfield]

DOESNT grounding the negative terminal result in a no spark condition?

 

Something isn't right there.  The negative side of the coil goes to the tach, and I believe the ignition box. I'm at work and don't have a wiring diagram, but I will confirm that later today.

  Mike

[Grundy]

I've got the wiring diagram for a 1970, and the negative just says "to tach". I'll try it that way... see what happens. Maybe the dude who put the engine in the car grounded the coil because it had a (-) on it, but it's not a good ground, and somehow it worked? I dunno. I'll have to check it with the meter tonight.

[MEK-Dangerfield]

I've got the wiring diagram for a 1970, and the negative just says "to tach". I'll try it that way... see what happens. Maybe the dude who put the engine in the car grounded the coil because it had a (-) on it, but it's not a good ground, and somehow it worked? I dunno. I'll have to check it with the meter tonight.

Maybe you just got lucky there? If the negative side of the coil is grounded, there is NO signal to the tach or ignition box. I just looked, and the "-" side of the coil does indeed go to the ignition box. Do you have any idea if this tach works? I remember a previous post where you said it wasn't functional.


  Mike

[Chryco Psycho]

_ coil terminal hooks to the ECU to control spark & the green tach wire connects to the _ side as well , do not ground it

[Grundy]

So apparently it was an optical delusion. When I got home from work I took a close look with the drop light. The negative goes to the distributor like it's supposed to. I was tracing wires and must have "jumped" over to another one that was grounded.