Tach install in no tach car

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Cribbs74

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I am nearing completion of interior and I have purchased a factory Tach cluster and gauge set for the center console. I need to wire it in and I assume the factory didn’t supply the wiring in the engine or main harness.

So, I have 2 questions, Has anyone done this conversation and can give me some tips and aecondly does anyone have a more clear and simplistic wiring diagram than the factory schematic? The factory schematic is n black and white, broken down to five or six separate pages with a poor key and unusual markings. It’s not that easy to follow.

Thanks!

Ron
 
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Currently equipped with 351C 4V 4BM, .060 over, roller cam, Sanderson block huggers, -AC
Members: Midlife (harness) and Rocketman (gauges) ) will set you up for success. 👌🏻
 
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A couple years ago, I converted my idiot light cluster to tach (via sending it to rocket man for conversion) and i installed the center console tri gauge cluster (had rocketman convert the alt meter to a volt meter.)
I had an oem factory tach cluster as well, but chose to go the conversion route, as it was a simpler process.

i guess it depends on the state of your car, and on how much work you are willing to do.

if I recall it correctly the factory tach cluster power plug in (on the speedo side) is smaller/shorter than the idiot light cluster (9 pin vs 14 pin?) as the factory tach doesn’t have the idiot light bulbs. ...so less circuits... npd used to sell the smaller plugs (I assume they still do)
i believe that you can’t change just one side of the cluster (without big time modifications) as the high beam indicator light is on different sides ( one is on the tach side and the other is on the speedo Side),
 

midlife

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NPD does continue to sell the short dash cluster connector.
The conversion of the underdash wiring takes me about an hour, but I have lots of experience. One resistor wire needs to be removed and the alternator lamp circuitry removed, as well as wiring up the 3 gauge center console. The main underhood harness cannot be converted, as the tach version requires two different power leads to provide the ammeter signals. My usual suggestion is to use the standard headlight harness and convert the ammeter to a voltmeter as per Rocketman.

I can do the complete conversion of the underdash harness for you in less time that it would take you to decipher the wiring diagrams and do the work yourself...
 
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Tach (with rocket man idiot light conversion to modern technology) is 2 wires. One to power (live when key is turned on), the other to the coil(i think negative side)

tri gauge cluster oem power goes through the IVR(pulsing power from the factory that effectively reduces power from 12 volts to about 6 volts)? The little rectangular metal box attached to the back of the gauge cluster (I actually installed a separate IVR just for the tri gauge cluster (but if you convert the alt to modern volt meter that gauge doesn’t have to run through the ivr
 
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Do the OEM tach's work different than an aftermarket tach? Wouldn't the OEM tach have a wire that gets a signal from the coil negative side? I know that some of the OEM GM tach I have worked on have a wire that just goes to the negative side of the coil. Does the OEM Ford tach somehow work in a different way? This seems to be so complicated to do, and I just do not understand why.
 
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I am, by no way an expert, but I recall reading something somewhere that if the factory tach craps out, your car won’t run potentially leaving you stranded...I believe some guys get around this by wiring in a bypass jumper wire that will let you run the engine to get you home). if I recall it correctly the factory tach has 3 wires, instead of the modern technology, 2 wires).
I think Rccinnovations.com (rocket man) website may have
some info on this
 
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My 2 cents worth, don't even waste time trying to convert a non tach dash to a factory tach. If you currently have idiot lights, take the idiot light pod out and send it to Rocketman (Bob) and have him convert it. His link is here on the website.
As for gauges, the ammeter needs to be converted to volts, again Bob can do it for you.
I went a different route with mechanical oil and temp gauges meaning I did not need to figure out how to wire the factory gauges in except the volt gauge and even I could manage that.
The result will be amazing. Factory appearing tach plus the idiot light. One note though, if you decide to upgrade the 194 bulbs to LED I highly recommend buying from Bill at www.HiPoParts.com. Buy the Elite set (I think that's the best one) BUT you will still need to keep a 194 bulb in the ALT socket. That is VERY IMPORTANT!
Here's a pic of my tach conversion.
 

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Do the OEM tach's work different than an aftermarket tach? Wouldn't the OEM tach have a wire that gets a signal from the coil negative side? I know that some of the OEM GM tach I have worked on have a wire that just goes to the negative side of the coil. Does the OEM Ford tach somehow work in a different way? This seems to be so complicated to do, and I just do not understand why.

I am, by no way an expert, but I recall reading something somewhere that if the factory tach craps out, your car won’t run potentially leaving you stranded...I believe some guys get around this by wiring in a bypass jumper wire that will let you run the engine to get you home). if I recall it correctly the factory tach has 3 wires, instead of the modern technology, 2 wires).
I think Rccinnovations.com (rocket man) website may have
some info on this

OEM tachs are an integral part of the primary ignition circuit. The Primary circuit is Battery -> Ignition switch -> Tachometer -> 'Pink' Resistor wire -> + side of ignition coil. If the OEM tach fails 'open' electrically it is like turning the key off. Most folks with an OEM tach carry a jumper with them so they can quickly 'bypass' the tach if it fails.

'Modern' or three wire tachs are seperate from the ignition circuit. They read the coil from the - side. Wiring is Switched power, Ground, - side of coil.
 

Mister 4x4

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I think it boils down to if you want that factory tach to work, you'll need to work with Midlife, but if you just want a tach that looks like a factory tach you'll need to work with TheRktman. Either way will give you a quality tach solution with easy-to-follow instructions for installing it into your car. You can't go wrong whichever way you go.

Here's my RCCI 'clock converted tach' and I couldn't be happier. The only difference is that if I decide to pull the instrument cluster out, I'll need to 'unplug' the tach connections, since they're separate from the factory harness.

Before, with the factory Clock/Speedo cluster:
dashrehab1.jpg

Surgery in-progress. Also upgraded to LED dash lights and swapped on a new 'glass' piece (rom OMS):
dashrehab4.jpg

After: All back together, workin' like a champ and lookin' like a million bucks!
dashrehab8.jpg

Hope this helps!
 
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I think it boils down to if you want that factory tach to work, you'll need to work with Midlife, but if you just want a tach that looks like a factory tach you'll need to work with TheRktman. Either way will give you a quality tach solution with easy-to-follow instructions for installing it into your car. You can't go wrong whichever way you go.

Here's my RCCI 'clock converted tach' and I couldn't be happier. The only difference is that if I decide to pull the instrument cluster out, I'll need to 'unplug' the tach connections, since they're separate from the factory harness.

Before, with the factory Clock/Speedo cluster:
View attachment 66238

Surgery in-progress. Also upgraded to LED dash lights and swapped on a new 'glass' piece (rom OMS):


After: All back together, workin' like a champ and lookin' like a million bucks!


Hope this helps!
Nice, and you have the same (type) steering wheel cover I have, very period correct!
 

Hemikiller

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My recommendation is you send your harness and clusters to Midlife and Rocketman respectively.

If you want to roll your own, there are a couple decent how-to articles floating around. I did the swap in '89 with nothing more than some boneyard parts and a wiring diagram. Now we have the internet.... :cool:

Posting for informational purposes, no guarantees these are 100% correct.

https://mustangsandmore.com/ubb/RichPajzerGauges.html

 

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Mister 4x4

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Nice, and you have the same (type) steering wheel cover I have, very period correct!
I love those covers - I had a nice one on my '82 Mustang's factory wheel, but decided to swap for a Grant GT Challenger wheel. I'm not a huge fan of the foam rim/grip, so putting the old school wrap cover on was a no-brainer. Unfortunately, that cover was found at O'Reilly's and wasn't big enough to fully cover the thicker foam rim/grip, so, I think I'll see if I can find one that fits a little better and re-install.

Mine's what I like to call a "Day Two Restomod," meaning that I've customized with modern performance goodies and creature comforts, but also the intent of keeping the cosmetic details looking as if I'd had one back in the mid-'80s when I first fell in love with these cars. Hence, the Cragar S/Ss & Cooper Cobras, Lakewoods, louvers, and Retrosound Model2 AM/FM/BT/USB stereo that looks like an old school Philco AM radio. I think the carbon fiber vinyl is probably the biggest detraction from that formula ("Wood grain" is for Country Squire Station Wagons!), as I can pretty much swap back to stock wheels and remove the louvers and I'll have a pretty stock-looking car.

I also swapped the Ammeter for a Bosch Voltmeter (because of the downward swiping indicator), but I think I would've probably been happier getting a converted Ammeter from RCCI to keep it all looking consistent. I'm still tossing around the idea of sending the Ammeter over to him for conversion. Come to think of it, I still owe him a center console clock, as well :)embarrassed:).

dashrehab9.jpg
 
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Probably redundant, but here is my 2 cents. My 73 coupe was nontach. Previous owner installed a monster tach. Looked cool, but I'm no racer. I bought a tach cluster on ebay. Bought some white stickers (vinyl overlays?). Got electric guages from autometer. Told midlife what I had and what I wanted. Now I have exactly what I want. I have zero electrical skills, but the guys on this forum are beyond helpful and keep my car running. Decide what you want, and they'll make it happen.

PS Tach from ebay was bad. midlife hooked me up with a guy who repaired it.
 

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Mister 4x4

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Probably redundant, but here is my 2 cents. My 73 coupe was nontach. Previous owner installed a monster tach. Looked cool, but I'm no racer. I bought a tach cluster on ebay. Bought some white stickers (vinyl overlays?). Got electric guages from autometer. Told midlife what I had and what I wanted. Now I have exactly what I want. I have zero electrical skills, but the guys on this forum are beyond helpful and keep my car running. Decide what you want, and they'll make it happen.

PS Tach from ebay was bad. midlife hooked me up with a guy who repaired it.
That's the same wheel I had in my '82 Mustang (but with a Running Horse Tri-Bar logo) - Love it!
 
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