Tach install in no tach car

[Stanglover]

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.

View attachment 66241

The main reason I bought the classic look wheel cover was because the factory rim is so thin, I couldn't get a good grip on it. With the cover, it feels great and I have better control of the car.

 

[MooseStang]

I need to do this for my 6 cyl later on.

 

[tpj71mach]

Members: Midlife (harness) and Rocketman (gauges) ) will set you up for success.

I had Midlife rework my harness and Rocketman upgrade the factory tach also

 

[71ProjectJunk]

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.

So, if you have a factory tach outside of the dash in your hands you can't just wire it up to work? You can't just put 12V to it and connect it to, in this case coil positive with the correct resistance and make it work?

 

[Don C]

So, if you have a factory tach outside of the dash in your hands you can't just wire it up to work? You can't just put 12V to it and connect it to, in this case coil positive with the correct resistance and make it work?

No, the Ford tachometer is a current sensing tachometer and is wired in series between the ignition switch and the coil. The tachometer has a small transformer in it and every time the points close a pulse is created across the primary windings in the transformer which generates a pulsed voltage that the electronics in the tachometer converts into a variable voltage that moves the tachometer needle.

This illustration shows how they are wired ('71 to '73 are similar):

 

[midlife]

If you have a Ford tach in you hands, you can wire it between the (now disconnected) coil lead and the coil itself and test that the tach works. If you have a dash cluster and want to see if the tach works, simply take the dash cluster out to the fender and wire it such that it is in-line with the coil lead. Remember: female connectors are always hot when energized if you need to determine which lead goes where.

 

[Cribbs74]

Well, I certainly have more options than I anticipated. I have spoken with Midlife, and have been given a quote. Now I just have to decide if I want to rip the harness out of my dash lol. It probably needs it regardless as it sat for 20yrs in a field and was home to various rodents. In fact one could call it a soup kitchen. I have replaced floors, headliner carpet and upholstery and it is much better now. I think the price is cheaper than the alternative which is spotty wiring.

Thanks to everyone who replied! You all are great!

Ron

 

[Lazarus]

+1 endorsement for the Rocketman idiot light conversion to tach, for what it’s worth.

 

[ScottM]

I have i6 car that I have swapped over to 351c. I have idiot lights and no gauges. Thinking of having rocket man do a tach conversion for me but what am I going to need to do in order to add modern gauges (volts, temp, oil)? What will I need to change on the wiring harness?

 

[Stanglover]

Reply to ScottM.
Lots has been posted on this.
My personal choice was to go with Bosch downsweep gauges as they looks somewhat similar to the factory ones.
I would definitely suggest mechanical oil and temp gauges. The volt meter was connected to a keyed 12V wire under the dash, may have been the radio wire, can't remember now.
May I suggest you start a new thread. It would be more visible that way.

 

[73CobraJet]

+1 endorsement for the Rocketman idiot light conversion to tach, for what it’s worth.

I did the Rocketman tach conversion and put in two gauges in the console where the broken clock is. Happy so far!

 

[Mister 4x4]

Reply to ScottM.
Lots has been posted on this.
My personal choice was to go with Bosch downsweep gauges as they looks somewhat similar to the factory ones.
I would definitely suggest mechanical oil and temp gauges. The volt meter was connected to a keyed 12V wire under the dash, may have been the radio wire, can't remember now.
May I suggest you start a new thread. It would be more visible that way.

I have the Bosch voltmeter in mine (pic above on the other page) but with the factory shroud/shield. I might consider swapping in the other Bosch gauges so they all match like yours. Looks awesome - well done!

 

[Stanglover]

I have the Bosch voltmeter in mine (pic above on the other page) but with the factory shroud/shield. I might consider swapping in the other Bosch gauges so they all match like yours. Looks awesome - well done!

Thanks Eric.
The hard part to install the Bosch (or similar) gauges was the bracketry needed. What I did was probably overkill, but that's me. Pictures have been posted before, but to save time, I can repost or send via pm.

 

[Mister 4x4]

I actually pulled mine apart and slid the inner workings of the gauge back into place using the factory mounting. Lost the cool 'Bosch' logo and 'Volts' lettering in the process, but I was more concerned with maintaining the downward sweeping needles than anything. Also swapped in LEDs, if you couldn't guess.

 

[Stanglover]

I actually pulled mine apart and slid the inner workings of the gauge back into place using the factory mounting. Lost the cool 'Bosch' logo and 'Volts' lettering in the process, but I was more concerned with maintaining the downward sweeping needles than anything. Also swapped in LEDs, if you couldn't guess.

View attachment 70871

At the time I did mine, I only had the center piece, no gauges, so I had to make the bracketry. I now have a set of gauges and looking at them, I believe it would not be too hard to adapt and swap in the new gauges.
Good job by the way and I see you got the best LED dash light out there.

 

[ScottM]

I did the Rocketman tach conversion and put in two gauges in the console where the broken clock is. Happy so far!

I did the Rocketman tach conversion and put in two gauges in the console where the broken clock is. Happy so far!

did you have to change anything on wiring harness? Did you just do mechanical gauges?

 

[cwalker509]

It is possible to do this yourself but you need to be able to read the wiring diagrams and possible source some parts (dash cluster connector which is smaller). The dash connector can be a problem to find. Midlife would be your best bet if you are not willing to tackle it on your own. First you need to unwrap the harness and get some tape to wrap it (the correct harness tape, not the sticky kind). What I did was pull the idiot light wires from the cluster connector and extend them in the harness to the center gages. I think i used my own connectors and converted a stock center gage (3 gages) for that connector. I used the Rocketmen tach conversion because Ford's better idea of tach wiring was STUPID. Unless you source the gage harnesses (under dash AND engine) converting to gage harnesses is simply not worth it and you would have to source the tach wire. I can't say mine works completely since i have not started the car yet but the voltage works (you also should have Rocketman convert your Ammeter to Voltmeter, I tapped into the radio circuit I think). Be sure when you convert the center gages that you use the correct wires for oil and temp. I think I swapped temp and ammeter wires in the underdash harness. Their is a separate underhood harness for oil/temp/ammeter (might be coil?)? The sensor connectors are different sizes so I need to reowk that little harness to swap those two sensor connectors.

 

[71coop]

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):
View attachment 66239

After: All back together, workin' like a champ and lookin' like a million bucks!
View attachment 66237

Hope this helps!

+1 on the clock-to-Tach conversion - I'm running that and its great. Also - like Stanglover - a +1 on a matching steering wheel (down to the faux-leather wrap).

 

[Stanglover]

+1 on the clock-to-Tach conversion - I'm running that and its great. Also - like Stanglover - a +1 on a matching steering wheel (down to the faux-leather wrap).

Ah, just realized I did not post a pic with my s/wheel showing in this thread, but like Mister 4x4 I have to same cover and love it.

 

[Paul M]

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

I had the factory tach configuration in mine, and it didn't receive the correct signal after swapping out ignitions. I used an MSD tach adapter to give it the correct signal. You are better off having one of the guys modify yours on this site. It will look neater less wiring and - an extra box.