Adding center gauges to a car that didn't come with them

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giantpune

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I'm working on a car that came with the idiot lights in the dash. I'm trying to figure out what all needs to be done to add the 3 center gauges.

If I want to keep the idiot lights working as they current are, I assume that means I need to find a spot to install the oil pressure and water temp senders. What I was thinking about for the water temp is the 351M water neck with extra ports. I've seen guys using that to add water temp sending units for EFI installs.

For the oil pressure sender, I'm still up in the air. My current idea was either hope the 351C has multiple ports for it, or else run an NPT tee to have the sending unit for the gauge and the existing switch for the dummy light. Does anybody have any suggestions for how to add that oil pressure sender? Where are the existing ports for that on a 351C?

And then the wiring. I have gotten the center dash with the 3 gauges and the little wiring harness. It terminates at an 8 pin connector with 7 pins populated. Is there anywhere to buy a spare male 8 pin pigtale that plugs into this? That would let me avoid cutting this wiring up.

Then for the other wires, there's a ground, a feed for oil pressure, and feed for water temp. I can figure those out pretty easily once I have the sending units in. The ALT gauge has red and yellow wires. Where would those measure across? And then there's a couple bulbs to light the thing up. Do I need to worry about the additional load that puts on the existing fuse? Hopefully 2 little bulbs isn't too much.
 
Gauges 101 in the tutorial has the most valuable information you will ever need, dumbed down for those of us that need to be taken by the hand. I used it as my bible for my gauge set install, and sent the amp meter to @TheRktmn to be converted to a volt meter, added new oil & temp senders with a T and kept the original oil & temp switches to feed the idiot lights. I also used a step down transformer from Amazon to power the oil and temp gauges (I used the 12 to 6v but there is one that is adjustable to 5v I would use). Do not use 12v for the gauges or you will blow them. Hit me up if you need more info. Pretty straight forward but take your time.

EDIT: I just remembered I wrote a thread here
 
Gauges 101 in the tutorial has the most valuable information you will ever need, dumbed down for those of us that need to be taken by the hand. I used it as my bible for my gauge set install, and sent the amp meter to @TheRktmn to be converted to a volt meter, added new oil & temp senders with a T and kept the original oil & temp switches to feed the idiot lights. I also used a step down transformer from Amazon to power the oil and temp gauges (I used the 12 to 6v but there is one that is adjustable to 5v I would use). Do not use 12v for the gauges or you will blow them. Hit me up if you need more info. Pretty straight forward but take your time.

EDIT: I just remembered I wrote a thread here
Thanks. And I didn't realize he was a member here. I have the original dummy lights coming back from him that got turned into a tach.
 
This is what I did.
First, I sent my idiot light housing off to Rocketman (RCCI) and had him convert it to tach with idiot light. An awesome upgrade!!
Next I constructed a mount for three Bosch down swing gauges (to look somewhat original) These are mechanical oil and temp plus a volt meter.
I added a T to the oil sender port, mounted the original sender on top and the mechanical COPPER tube off the T. I would NOT recommend using the nylon tubing they supply.
For the temp, I removed the unused 3 port vacuum sensor from the w/pump and installed the light sender there. This is less accurate as pump temp will be lower. I installed the mechanical sensor in the original position. NOTE: be very careful with this tube, it is quite delicate.
To get it all through the firewall, the only plausible location was as seen. I used a grommet with two hole in it which was intended for the fuel and brake line through the left shock tower (NPD sell it). I did make one boo-boo and that was I didn't add a loop in the copper tube to take up engine roll, but there was enough slack that it has not been a problem.
There has been many posts on this. Take some time to search.
Here are a couple of pics of my set up.
Stock gauges CAN be changed and that may be easier for some.
 

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Last edited:
Semi-related question for you guys. My dummy light tach conversion came back in today. When I went to stick it back in my cluster, none of the screws in my little magnetic tray seem to fit in the hole.

What does the screw that holds the voltage regulator to the back of the cluster look like?
And does anybody know where to buy a spare in case I lost the correct one? :D
 
There we go. I got the oil pressure and water temp gauges working. Maybe one day I will send the set off to have the center one converted to volts.

I'm getting 6v from adding a wire to break out from the voltage converter behind the main cluster. That runs over to the center of the dash through a 4 pin connector to feed the gauges. Then I ran a couple new wires back out to the engine. For the sending units, I used a tee and running dual oil pressure senders. And I used one of the thermostat housings with NTP ports to add an extra water temp sender.

For the lights, I made up a harness that plugs inline to the harness for the heater illumination. That lets it add 2 more bulbs without having to cut into any of the car's existing wiring.

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Gauges 101 in the tutorial has the most valuable information you will ever need, dumbed down for those of us that need to be taken by the hand. I used it as my bible for my gauge set install, and sent the amp meter to @TheRktmn to be converted to a volt meter, added new oil & temp senders with a T and kept the original oil & temp switches to feed the idiot lights. I also used a step down transformer from Amazon to power the oil and temp gauges (I used the 12 to 6v but there is one that is adjustable to 5v I would use). Do not use 12v for the gauges or you will blow them. Hit me up if you need more info. Pretty straight forward but take your time.

EDIT: I just remembered I wrote a thread here
I sure appreciate the information about not sending 12 volts to gages as I am using original gages from ebay. Where should I source the 5 volts from? Being an old GM guy I never ran into this problem. The non working tach was sent to convert to 3 wire and ammeter was converted by Rocketman with a voltage overlay sticker. I am rehabbing my 1971 fastback also with a 4spd as a manual transmission makes me feel like 26 instead of 76 years old. I replaced the rusty shock towers with ones from West Coast Cougar that were cut off from old Cougar. These were like new and would reccomend West Coast Cougar to everyone. Thx, Bill
 
Where should I source the 5 volts from?
In my post above yours, one of the pictures is the connector that plugs into the back of the main gauge cluster. The back of that cluster already has the voltage regulator and some 6v power.

In my photo, the top row, 3rd pin from the left has a blue wire coming out the back. I added that terminal and that blue wire. That pin is where the power comes from on factory harnesses for the center gauges.
 
This is what I did.
First, I sent my idiot light housing off to Rocketman (RCCI) and had him convert it to tach with idiot light. An awesome upgrade!!
Next I constructed a mount for three Bosch down swing gauges (to look somewhat original) These are mechanical oil and temp plus a volt meter.
I added a T to the oil sender port, mounted the original sender on top and the mechanical COPPER tube off the T. I would NOT recommend using the nylon tubing they supply.
For the temp, I removed the unused 3 port vacuum sensor from the w/pump and installed the light sender there. This is less accurate as pump temp will be lower. I installed the mechanical sensor in the original position. NOTE: be very careful with this tube, it is quite delicate.
To get it all through the firewall, the only plausible location was as seen. I used a grommet with two hole in it which was intended for the fuel and brake line through the left shock tower (NPD sell it). I did make one boo-boo and that was I didn't add a loop in the copper tube to take up engine roll, but there was enough slack that it has not been a problem.
There has been many posts on this. Take some time to search.
Here are a couple of pics of my set up.
Stock gauges CAN be changed and that may be easier for some.
I love those Bosch guages - I replaced my Ammeter with a Voltmeter and just wired it as aftermarket, but I pulled the gauge apart to fit in a little better with the other factory gauges. I'm thinking I might eventually replace the others with their Bosch counterparts and do the same thing, but I'm happy with it for now.
dashrehab9.jpg
 
I'm working on a car that came with the idiot lights in the dash. I'm trying to figure out what all needs to be done to add the 3 center gauges.

If I want to keep the idiot lights working as they current are, I assume that means I need to find a spot to install the oil pressure and water temp senders. What I was thinking about for the water temp is the 351M water neck with extra ports. I've seen guys using that to add water temp sending units for EFI installs.

For the oil pressure sender, I'm still up in the air. My current idea was either hope the 351C has multiple ports for it, or else run an NPT tee to have the sending unit for the gauge and the existing switch for the dummy light. Does anybody have any suggestions for how to add that oil pressure sender? Where are the existing ports for that on a 351C?

And then the wiring. I have gotten the center dash with the 3 gauges and the little wiring harness. It terminates at an 8 pin connector with 7 pins populated. Is there anywhere to buy a spare male 8 pin pigtale that plugs into this? That would let me avoid cutting this wiring up.

Then for the other wires, there's a ground, a feed for oil pressure, and feed for water temp. I can figure those out pretty easily once I have the sending units in. The ALT gauge has red and yellow wires. Where would those measure across? And then there's a couple bulbs to light the thing up. Do I need to worry about the additional load that puts on the existing fuse? Hopefully 2 little bulbs isn't too much.
Check with Midlife Harness to see if Randy has the male connector that you are looking for. If he can't help you get ahold of me as I have the plastic connector and the pins that are used with it. Please check with him first as he is the genius about our 7173 Mustangs. Thx, Bill
 
Reading this thread is quite eye opening for me as about 40 years ago I swapped out my 72 vert main instrument cluster and center panel with gauges. I stripped all items including wiring harness from a scrapyard car and followed the wiring diagram included with the shop manual set to complete the conversion (my dealer basically advised against doing it). To my surprise, it worked exactly as if it were factory original, and still does to this day. However, very sporadically the RPM gauge temporarily stops working. If anyone knows what possibly could cause this, please let me know what to check.
 

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