[Blackshadow]

Need some tachometer help I purchased a used 1965 6000rpm Shelby tach. 3 wires (blue, red, and black). I figured blue is the light, red dist side of coil and black would be ground so installed this way as stated above. Car wouldn’t start but needle on tach moved as it was cranking over. Unhooked tach car ran great but if I touch the black wire to ground it would make the tach needle register but would kill the engine. So I now thinking the tach must be bad is this the right assumption? Or did I miss something? :headscratch:

 

[rocky289]

Not a expert on this but I would think the black wire would got to the distributor side of the coil & the red would be the power feed.

 

[Blackshadow]

Finally got back to working on this problem this is what I figured out. the tach is a inline tach so I wired it between the ignition switch and the battery side of coil, seem to be working fine. Still not sure how it works without any ground or how the tach is driven... but hey it working. Thanks Rocky289 for your suggestion :bigthumbsup :happypills:

 

[davestangman]

You are correct the tach has to be wired inline, just make sure you run the wire from the ignition switch threw the factory wire out to the coil as this is a resistor wire and it can burn out the tach with out the resistor .

 

[Blackshadow]

yep got it. it is the pink wire...