68 Tachometer Question - Vintage Mustang Forums

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post #1 of 4 (permalink) Old 02-11-2005, 10:30 PM Thread Starter
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Hi there, I was just wondering, I got a 68 cougar that has a Tachometer , Im thinking of pulling this one out and putting it in my 68 Mustang. Do you think this will work? My cougar has 302 and my mustang has 390 engine. The guages looks similar, my only problem is how will I wire this one up. On my cougar since it came with the tach, the wires are there. I looked at my mustang cant really find the wire like my cougar. Pls anyone let me know how I can do this...
thanks in advance

68 302 4v High Country Special Mustang (Mark Anthony)
68 GT 390 Mustang Coupe (Caroline)
68 GT 390 California Special Mustang (Sally)
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post #2 of 4 (permalink) Old 02-11-2005, 11:19 PM
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Since you do NOT have a gauge pod with a printed circuit, you do not have the problem of an underdash wiring harness with a pinned connector which precludes a factory tach (like in a 69 and 70). As long as you can mount the tach in the gauge panel and wire the illumination, I would think you can run a wire from the coil secondary + (?) post through the firewall and to the tach, bypassing the underdash wiring harness. The size of the engine does not matter as the tach runs off the coil - 4 firing pulses to a revolution (2 rotations of the crank for every one rotation of the cam, since it is a 4 stroke motor).

Who knows, maybe a guru here would be able to tell us that the underdash harness is the same for tach and non tach and just fish a violet wire out of the loom and plug it in.

Rebuilding a classic mustang is a reality check on your individual state of perfection.
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post #3 of 4 (permalink) Old 02-12-2005, 01:23 AM
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Original tach and non-tach under-dash and firewall-to-headlight harnesses were different for the 68's. Believe it is also true for 67 and 69, no clue on other years.

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post #4 of 4 (permalink) Old 02-12-2005, 01:30 AM
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The tach would work fine, but it will take a bit of fabrication to make it fit in your Mustang's instrument housing as the Cougar housing isn't a straight drop into the Ford. The cup for the tach is shaped differently for the tach versus the two guages. You can slice the tach cup off flush with the rear surface and graft it onto the Mustang housing (after similar slicing off the guage cup). A wire-feed welder makes short work of the grafting. While tach and non-tach harnesses are differnt, adding a tach is simple. To wire the tach in you'll have to cut the wire leading from the ignition switch to the coil about 2-3 inches from the ignition switch. The ignition switch lead attches to a red with stripe wire on the tach and the black wire on the tach attaches to the wire leading to the coil. Factory tachs are wire in series, not parallel to the coil.

In the instrument cluster I modified, I also grafted an instrument cup onto where the clock sets and using a mix of 67 & 68 guages, had Fuel, Water Temp, and Oil Press across the top. I used the Cougar Speedo as well as the Tach so the slight lettering differences were not noticable between the large gauges. If you use a Cougar Speedo with trip, you can use the Cougar lenses, but their locating tabs are slightly off from the Mustangs, but easily fixed by filing a couple of small notches. Their shape is also different... not noticable in place. I used Mustang center buttons on the lenses inplace of the Cougar centers (attached with silicone).

I took just one evening to take care of all the surgery and wire mods.

Tom (Johnson) Kubler, a.k.a. 289fan, HiPo289fan, TJinSA, Fy A. Thyrio, & various other unmentionable names.

The A.B.C.s of the '66 GT350- Accelerometer, Beatermeter, Clock

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