Wiring a SW Tachometer

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In the Shed
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Wiring a SW Tachometer

Post by In the Shed »

Hi Folks,
Got an old Stewart Warner tacho that I want to install. I am unable to locate a wiring diagram for something of this age so calling on others to see if I am on the right track?

In the picture (how it came) I have marked up the blue wire for tacho backlight feed and the earth (two wires already joined). Backlight confirmed it works. Presumably the other wire (red sleeved wire) goes to the coil wire that goes to dizzy. That wire would get 12 volt (positive) when points open then negative when points closed, creating the pulse.

Most of what I have found mentions a separate 12v feed. I don’t want to damage it. Appreciate your input.
Regards
Stephen
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Errol62
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Re: Wiring a SW Tachometer

Post by Errol62 »

Hi Stephen,
I reckon green wire to coil negative, red to ignition power (coil positive), black to good engine earth.


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Brett027
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Re: Wiring a SW Tachometer

Post by Brett027 »

Try this.
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Harv
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Re: Wiring a SW Tachometer

Post by Harv »

Make sure the little selector switch on the back is set to "8". For the first 10 minutes or so you can pretend that you have a high RPM speedway engine. Then set it back to "6".

... not that I ever did that :lol: :oops:

Cheers,
Harv
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In the Shed
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Re: Wiring a SW Tachometer

Post by In the Shed »

Thanks guys. A little more digging required I think.

Stephen
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Blacky
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Re: Wiring a SW Tachometer

Post by Blacky »

I reckon Clay has it nailed
When you're faced with an unpleasant task that you really don't want to do, sometimes you just have to dig deep down inside and somehow find the patience to wait for someone else to do it for you.


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In the Shed
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Re: Wiring a SW Tachometer

Post by In the Shed »

Thanks Blacky
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Errol62
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Re: Wiring a SW Tachometer

Post by Errol62 »

Moment of truth when you turn the key......

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gledge
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Re: Wiring a SW Tachometer

Post by gledge »

I suggest that the green and black are the power for the light and the tach power joined together as if who ever wired it up last just had the back lighting on with ignition.. maybe …I would lose all the tape and check weather the colour coding has been changed anywhere under that tape..





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Re: Wiring a SW Tachometer

Post by In the Shed »

Good call Gledge
A previous repair
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Re: Wiring a SW Tachometer

Post by In the Shed »

Couple more pics inside. The blue & green wires for the Edison screw globe holder are insulated from the rest of the unit as board is similar to Bakelite. Ohm meter confirms same. Only leaves red and black.


Thinking two joined with circular terminal earth, blue to dash light and red single to dizzy side of coil???

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Re: Wiring a SW Tachometer

Post by In the Shed »

Try again
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Re: Wiring a SW Tachometer

Post by Blacky »

So green and blue are to the light and red and black to the mechanism ???
When you're faced with an unpleasant task that you really don't want to do, sometimes you just have to dig deep down inside and somehow find the patience to wait for someone else to do it for you.


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Re: Wiring a SW Tachometer

Post by In the Shed »

Yes Blacky
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Harv
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Re: Wiring a SW Tachometer

Post by Harv »

May have to work this problem by finding the model number then a specific wiring diagram.

Prior to 1994, the model and date code was stamped on the body of the gauge e.g:
970B M8
970B is the part number and M8 is the date code (August 1968).

After 1994, a 4-digit code was printed on the label, usually perpendicular to the part number e.g.:
0206
The first 2 digits are the year, 2002. The second 2 digits are the month, June.

As a fall-back, contact SW directly:
https://www.stewartwarner.com/contact-us/

Cheers,
Harv
327 Chev EK wagon, original EK ute for Number 1 Daughter, an FB sedan meth monster project and a BB/MD grey motored FED.
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