Wiring 67 factory tach?

Every retailer I speak to (of course) claims I need $700 worth of wiring harnesses to hook up the 67 factory tach cluster I acquired last year.

Common sense tells me this is nonsense, but I don't know for sure... has anyone rigged a factory tach with existing harnesses, or does anyone know if you feasibly can?

Thanks, again.

Reply to
67RMod
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I thought the wiring harness was the same for all the 67's. I have a 67 with a tach, (factory 390 but when I bought it in 77, it had a 289) and the wire harness looked the same to me as other 67's I've seen without a tach.

I'd look on page 19-5 of the shop manual, and then at the wiring harness for a red-green stripe wire and a red-yellow wire. You should be good to go.

C. W. Robertson

1967 Mustang Fastback Daily driver Almost 300,000 miles

67RMod wrote:

Reply to
C. W. Robertson

Entering into the unknown, V'ger seeks information used to maintain his Vintage Burgundy 1965 Ford Mustang 2+2 w/289 ci 4v oem A Code V8, C4 Trans, 16x8" Vintage 40 wheels, with BF Goodrich gForce T/A 225/50ZR16 tires, American Racing "Mustang" Centercaps, and a whole lot of other stuff; )

Reply to
D. Willson

Nice ride... you don't see many 390s around.

Yeah, that's what I would have thought. I can't imagine having to yank and replace all those harnesses for one instrument. Seemed ridiculous. I refused to believe the retailers.

Hey, thanks a lot!!! I was going to ask if you had a schematic to reference, and there it is. Good deal. A project for the weekend!!

Take it easy Jason

Reply to
67RMod

Vintage Burgundy 1965 Ford Mustang 2+2 w/289 ci 4v oem A Code V8, C4 Trans,

16x8" Vintage 40 wheels, with BF Goodrich gForce T/A 225/50ZR16 tires, American Racing "Mustang" Centercaps, and a whole lot of other stuff; )
Reply to
67RMod

C.W.,

On the back on the tach in the center, there is just a red and a black wire, both of heavier gauge. Presumably these go to the alternator. Do you (or does anyone) if this is true, and if so, where they hook up on the alt.? If I don't find the matching wires in the dash, I can certainly make some, but I still am not sure where they end up connecting to the alternator. Any help would be greatly appreciated.

C. W. Roberts> I thought the wiring harness was the same for all the 67's. I have a 67

Reply to
67RMod

Why would a tach be hooked to the alternator?

Reply to
CobraJet

You have 13 minutes to respond before I go beddy-bye. We can pick it up tomorrow otherwise.

Reply to
CobraJet

I thought tachs in 60s cars were hooked to the alternator. I heard me pappy say that once. Per'aps I 'eard him wrong.

Reply to
67RMod

Thanks... talk to you later on.

RMod

CobraJet wrote:

Reply to
67RMod

Yep, you did. Are there any markings on the tach where your red and black wires are attached? They go on studs?

Reply to
CobraJet

Ok... I finally (and gingerly) got the case open, and found the following - the red and black wire come out of the middle of the case. There are studs on the case, but they are unmarked, and do not hook up to anything, they just keep it together. The red wire is male, the black is female, incidentally.

They hook directly into a small PCB in the tach. There is a smaller red wire from the PCB to the center of the tach, to a small circular spring / coil / counterweight assembly connected to the "needle shaft". There is a smaller black wire from the PCB, soldered to the "chassis" of the unit, obviously ground. That's all I see.

One thing is, the tach needle is sort of ... loose. It doesn't always rest on zero. It usually rests on 5 or so. I don't know if putting the correct current to it would remedy that or not.

The assembly and all solder points and other components look intact, and it's all as clean as a whistle inside. Nothing looks cooked or damaged.

Reply to
67RMod

OK, good start. What the Ford tach is, is an ammeter. The ignition current goes from the key switch into the tach, then out of the tach to the firewall connector, then from the engine side of that to the + side of the coil. All the wire in this circuit is red with a green stripe. This is called a series circuit, and if the factory tach burns up, the car will not run.

In a non-tach car, the red/green wire goes from the switch and terminates into a female bullet connector, which also has the red/yellow wire previously mentioned. *That* wire is not used in this circuit, but can help identify the connector. This is plugged into a

*male* bullet connector, which has the other side of the r/g wire going to the firewall. Whan a tach is added, the bullet connector is pulled apart and tach wires plug into the two ends, creating the series loop. In your case, I suspect that the non-stock red wire should go to the female bullet connector, and the black wire goes to the male bullet side.

There's more, but first see if you can find this line leading from the back if the igntion switch.

>
Reply to
CobraJet

A lucid explanation. How about that. I've heard so much b.s. about this...

I see the red/green wire going -into- the switch.

Coming out, a there's spade connector on the side, with a purple and a brown wire; from the stud, a couple of my own, and a large factory connector that appears to be black w/yellow stripe that and disappears into a nest of wires under the dash.

I looked around, and found the grommet right next to the cowl that contained both the red/green and red/yellow wires coming IN, but nothing going out.

Hmm...

Reply to
67RMod

Into, out of, what's the difference? We talk in flow of current directions. The only wires leading into the switch are the one(s) that have 12 volts all the time (constant).

Is there a bullet connector there? You may have to unravel some harness tape/wrap to track the red/green wire. Do you have a test light or VOM?

Reply to
CobraJet

Ok, gotta back up here. I said I saw the red/grn wire going into the ignition switch. After cleaning it up and getting both eyes on it, I see it's a red/blue wire. I used to fit better between my aftermarket bucket seats and the steering wheel.

The only red/grn wire I can positively identify is currently hooked up to the + side of the coil. I wasn't the one who hooked up the tach or did most of the wiring in the car (long ugly story) so I have to determine exactly where it's going. I have an aftermarket tach.

I looked again at the two other grommets on the firewall, and found red/white, red/blue (two of them?), red/yellow but no red/green. The red/green I found hooked to the coil was a heavier gauge than the others, maybe 14 instead of 18. Is that the one I'm looking for?

I find bullet connectors, but none so far with red/green or red/yellow. I think I've found both wires, though. I tell you, it's been fixing one mess after another with this car ever since the "Classic Mustang expert" (who specializes in Boss and Cobra Jet cars, BTW ;) finally put it together enough such that I could drive it AWAY from him.

This guy cannabalized someone's 69 Shelby to the tune of $50,000. Evil bastard.

Yes, I do have one; I will need to get batteries for it. And no bullet connector that I can immediately see. I will need to get the battery and get myself situated under the dash.

Reply to
67RMod

That's the starter solenoid wire.

Push the car instead of drive it. Good for some weight loss.

Take a hard look at the two red blues. One might be green. It would go to the same 3-pin plug as the red/white.

Yes, but you are looking for it continuing back under the dash. It has to originate from the ignition switch, unless someone has monkeyed wih it.

Get the seat out from underneath with a deep 1/2" socket.

Reply to
CobraJet

Ah..

I just quit smoking... what can I say... 8-)

Ok.... they're grimy. At least that would tell me which was the right one. I was cursing myself for not finding what IS there.

Alright.. I don't think they have. Why would they?

Seems like I'll need to.

Thanks again for the help, CJ. I will get deeper into it tomorrow, re-read your stuff, and let you know what I come up with.

Reply to
67RMod

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