Topic: 67 Tachometer in an S Code GT, 6000 RPM?

[wunderwerks]

A friend just picked up a 67 instrument cluster that has a 6000 tach in it.  He is finishing up his 67 S code GT and was hoping this would be the correct tach for his car.  Ford parts book shows the 6000 tach is used only in '67 and listed "for V8 Special 4bbl".  He's also concerned about the underdash wiring harness must be specific for a tach equipped car.  He doesn't know which harness he has already installed if there is a difference.  Advice from anyone?

[67gtasanjose]

1st, yes I believe the 6K tach would be a correct OPTION to go on a 390.
2nd, yes, the harnesses are different for tach cars, the alternator harness and the underhood harness and the instrument harness. Only the tailight harness doesn't care if it had a tach (that one has other options that determine correctness).

If the underdash harness has the connections for the two tach leads, it is correct. If it doesn't, I believe Randy (Midlife) can convert it for you.

[midlife]

1st, yes I believe the 6K tach would be a correct OPTION to go on a 390.
2nd, yes, the harnesses are different for tach cars, the alternator harness and the underhood harness and the instrument harness. Only the tailight harness doesn't care if it had a tach (that one has other options that determine correctness).

If the underdash harness has the connections for the two tach leads, it is correct. If it doesn't, I believe Randy (Midlife) can convert it for you.

Yup, I do that all the time.  I can convert the underdash and the dash cluster harness, but not the headlight harness.

If your friend's car was running before buying the dash cluster, then the wiring in the car would be specific for his dash: tach or standard.

[midlife]

I need to clarify my remarks.

Oh yes, conversions can be accomplished, but I don't like to do it for a variety of reasons.
(1) A lot of headlight harnesses are in poor shape due to 40+ years of exposure to heat and the elements
(2) To convert correctly, one must pull the ammeter lines from one end of the harness to the other: a real pain.
(3) The VR needs a fourth line, requiring one line to be inserted from one end of the harness to the other: again, a real pain.
(4) Why do this when the reproductions are just a few dollars more than my refurbishment costs?

Fundamentally, there's nothing to prevent a conversion, only whether it is time and cost effective to do so.

Sorry...I should have been clearer in my post.

[RocketScientist]

The conversion from non-tach to tach is fairly simple but it involves running one or two extra wires. They can be discretely hidden into the existing wiring looms and only those looking hard enough will pick it up. To me, having a really cool looking tach outweighed the time and effort to do so and the loss of originality. We didn't have to modify the headlight harness and so the original cluster can go back in if I want to. I studied the wiring diagrams but was lucky enough to have someone who knows old Ford wiring systems.

[midlife]

The conversion from non-tach to tach is fairly simple but it involves running one or two extra wires. They can be discretely hidden into the existing wiring looms and only those looking hard enough will pick it up. To me, having a really cool looking tach outweighed the time and effort to do so and the loss of originality. We didn't have to modify the headlight harness and so the original cluster can go back in if I want to. I studied the wiring diagrams but was lucky enough to have someone who knows old Ford wiring systems.

I'll respectfully disagree with you if you're talking about keeping everything stock as Ford intended.  The conversion from standard to tach involves not only installing a tachometer, but the removal of the ammeter and installation of an alternator indicator light.  That light requires a 15 ohm resistor wire in its circuitry.  No one that I know of sells a 15 ohm resistor wire of the proper resistance per foot in the lengths required for Ford.  I had to spec out the wire to a specialty shop and had to buy 2000 feet of it to reach the minimum purchase price of $500.  The indicator light also requires a change of wiring at the voltage regulator, tied into existing wiring of the headlight harness so that signal can feed into the underdash harness. 

Yes, you can make the tach work by simply removing the pink resistor wire where it starts (at the ignition switch and moving it to the tach) and installing another wire in its place to the tach as well.  Only doing this, however, this is not as how Ford designed their system. 

[Bob Gaines]

I'll respectfully disagree with you if you're talking about keeping everything stock as Ford intended.  The conversion from standard to tach involves not only installing a tachometer, but the removal of the ammeter and installation of an alternator indicator light.  That light requires a 15 ohm resistor wire in its circuitry.  No one that I know of sells a 15 ohm resistor wire of the proper resistance per foot in the lengths required for Ford.  I had to spec out the wire to a specialty shop and had to buy 2000 feet of it to reach the minimum purchase price of $500.  The indicator light also requires a change of wiring at the voltage regulator, tied into existing wiring of the headlight harness so that signal can feed into the underdash harness. 

Yes, you can make the tach work by simply removing the pink resistor wire where it starts (at the ignition switch and moving it to the tach) and installing another wire in its place to the tach as well.  Only doing this, however, this is not as how Ford designed their system.

+1. I have done them before in past years for myself. It is tedious work and I believe that it is not reasonably practical for a business to get a return on the investment for the reasons that were outlined in post #3. A labor of love and a labor for business are two different scenarios  .

[RocketScientist]

Hi Guys, I completely agree with you but I still stand by my earlier comments. There was no modification or cutting of the dash wiring harnesses and the few wiring changes in the engine bay, around the voltage regulator, would only be picked up by a experienced person who knows Mustang wiring. I bank on the fact that 99.9% of the population sees something that looks correct and so assumes that its correct!!! The tach, including all indicator lights are fully functional as per Ford specs and it is much better to look at than an ammeter (so I guess that its a 'period correct' modification). I had no desire to damage my existing wiring and I happily achieved that aim.

I made it seem simple but I had to do a lot of ground work to understand wiring systems and the changes required. Once I worked out a plan with the auto electrician the changes only took a few hours - I guess that I was lucky enough to find someone who knew their stuff!

[67gtasanjose]

Waking up an older post, I think this request best fits in here, rather than a new thread...Moderaters may or may not agree

Specifically, I am looking for original, UNALTERED images of the wiring harness peferably IN PLACE on the back side of the cluster of a 67 6K tach dash car.

* I already have the original tach dash harness with a green tag, it has "10B942D" & "TSX" on the tag. (For what it's worth, I am using all original main dash harness and headlight harnesses, not "converted" harnesses or reproduction harnesses)

* I think some of the taped areas are missing some of the tape, particularly in the area under the wiper switch. This is the focus of my need. Do I add tape or simply just strap it down?

* There is a wiring strap that is on the backside of the cluster, below the LS turn lamp. Would like a focus on that area, (VR area) to see what other original taping would look like.

* The images I see of Alloy Metal reproduction tach harnesses do not look like what I can see this one looks like so the reproduction harness looks different to this example.

* I found this image, but could use more detail of what is hidden behing the voltage regulator. This picture looks like a great example of what my harness likely looked like before some tape was removed. A flip-side view would help tremendously.
http://www.allfordmustangs.com/forums/attachments/classic-tech/82381d1257023219-1967-mustang-instrument-panel-wiring-pics-1-387.jpg