In my experience, having built and owned these old Mustangs for over FIFTY years now, the original AMP gauge is about as useful as tits on a boar hog. Swapping to a voltmeter gives you a good view of what your electrical system is doing.

If your battery is at six volts, it might show it is charging, but no idea of the available voltage.
A voltmeter lets you know exactly what is going on. Just rev the engine to see how well it is charging. Voltage readout tells you the system is fine or not.

It is rare to even see an original ammeter that moves at all, except maybe when the turn signals are flashing.

wsinsle wrote:

Found some old pics. I bought a 2" Sunpro volt meter and took the face off.

Mounted on back like the Amp meter. May have drilled different holes.

Put the original dash cover on. Issue, I can't find a white face meter with top dial.
 

 
I want to give you all an update:  I found one of these gauges that Winsle posted cheap so I decided to try it, before I committed to the RC conversion.   He is correct.  It was super easy to mount, it bolts in, no cutting, no drilling, the hardest part was opening the gauge up.  SUPER simple.  That is where it ends.  I decided to go one step further and play with the lighting.  That is a major problem.  The light bleeds through horribly.  A stark contrast to the rest of the gauges in the panel, none of which light up great to start with.   Otherwise, the gauge has the same depth as the original.  If you've had one apart before, you noticed a lip on the bottomside of the original gauge.  This lip mates up with another lip on the bezel, and it's purpose is to direct light.   

Too me, it reinforces the choice to have the conversion done with the original gauge.   

If this (the lighting)doesn't matter to someone else, you can have this brand new cp7985 innards to do this simple, easy, conversion.   Just pay the shipping. Your finished product will look exactly like Winsle's picture.
I suppose I could try to take a picture of the lighting if someone on the forum wishes.

John Ha wrote:

You could also make your ammeter more useful.  I fixed mine by installing a new yellow wire on the output terminal of the alternator and connecting the other end to the yellow wire on the right (pass) side of the engine bay just aft of the solenoid (you'll need a bullet connector there).  I started with a 10 foot length of 16AWG and gradually reduced the length until I saw (with the car not running) a small ammeter deflection when I pressed the brake pedal to turn the brake lights on.  Then I dressed the new yellow wire (routed and secured it).

I've read about doing that, and will probably do it to mine too. On my 69 the wire is #37 which is 12ga. The next year was the first time that Ford put a fusible link on Mustangs, and just the link was 16ga., with the wire still 12 ga. Any idea what length 16 ga wire you ended up with? It would help me calculate the resistance. I've heard that the contacts in the firewall connector for the gauge (on wires 654 and 655) are the big culprit, and should be cleaned.

Did everyone misunderstand what I posted?  The problem is it lets in way too much light compared to the stock gauges because the reflector lip is missing, plus that angled piece of metal on the bottom of the stock gauge is there most likely for light reflection also.   What I am saying is it looks way out of place compared to the rest of the stock dash gauges at night.    Maybe some could live with that.  I will post a pic shortly.

Greg B - Yes, I misunderstood.  Seems some sort of shading is needed. 

Can you paint part of the blue bulb socket insert an opaque color to mask some of the light going to that area?  Maybe make a masking tape template to experiment and determine where the paint needs to be applied?

Last edited by John Ha (2/27/2024 10:46 AM)

Greg B wrote:

I know some work could be done to make this better, but I'ma go with the other.   Ignore the turn signal light, going back and forth I left the cardboard tube off the test dash.

 
Try some strategically placed black electrical tape to reduce the over powered lighting before painting it.
Take a close look at ammeter shading on both pieces of my 65 cluster.
This is factory 65 paint shading.

Last edited by Nos681 (2/28/2024 4:05 PM)

Whatever shading is used, I install LED bulbs.  Even those little incandescent bulbs can get hot and cause damage.