Interesting Article on Ammeter vs Voltmeter

[7E-Bodies]

I'll be facing this decision before too long...

https://www.hemmings.com/stories/2021/10/01/how-and-why-to-replace-an-ammeter-with-a-voltmeter-in-a-vintage-mopar

[chargerdon]

In my 74 Challenger, i replaced the ammeter with a Sun Voltmeter...both were 2" diameter round gauges, so it was fairly easy.   I also ran a 10 gauge (still have the original 47 amp alternator so 10 gauge is plenty) wire from the alternator to the starter relay, and disconnected the factory 12 gauge that was attached.    I believe this corrects the problem.

On my 66 Charger, i did not want to replace the ammeter because its a very unique gauge with electroluminescence.   So, i looked at the ammeter itself apart and realized that the gauge itself is VERY strong, nothing but a solid shunt bar inside it...  The needle touches nothing and is pulled either direction by the magnetism in the electricity going either to the battery or from the battery in the shunt bar.   HMMM   

So the real problem is the 12 gauge wiring from alternator which is far to light, thru bulkhead with its corrosion prone spade/lug connectors to the ammeter, and then the ammeter 12 gauge back thru the bulkhead connector to the starter relay !!!!   I replaced those wires with 10 gauge run thru the firewall with a grommet bypassing the bulkhead connector, to the ammeter.   Making sure the connection was clean and tight and with dielectric grease.    Then a new 10 gauge wire, back thru the firewall grommet, into a 40 amp replaceable fuse then to the starter relay.    On this car, i do NOT have air conditioning, or power windows or seats, and the alternator is still an original (rebuilt) 37 amp alternator.      Ohh one last thing is that i replaced the entire in dash wiring harness with a new one as i was seeing several "burnt" wires going into that old bulkhead connector.  Nice thing about the new harness is that it included a new bulkhead connector panel.   So i feel that this upgrade to 10 gauge, new wiring harness (didnt use the ammeter wires in it) and bypassing the bulkhead connectors allows me to retain the original ammeter.

So, i have done the upgrade differently but feel safe for both !!!

[Dakota]

This change is definitely worth doing from a reliability standpoint.

My bulkhead connector was melted and toasted (I think it was terminal 16) when i opened it, so my electrical system was well down the road towards failure.  I have a factory a/c car that now has an electric fuel pump.   I had the voltmeter conversion done, did the ammeter bypass as spelled out by MAD Electric, and have since added relays for headlights (high and low), fuel pump, and a/c clutch in a plastic box that's tucked behind the driver side headlight.  The wiring harnesses are all new.

The new alternator and all the wire routing are not even remotely stock looking.  It's not a numbers car or anything really special, but I trust it will get me from A to B without electrical issues.

[dodj]

I'll be facing this decision before too long...

https://www.hemmings.com/stories/2021/10/01/how-and-why-to-replace-an-ammeter-with-a-voltmeter-in-a-vintage-mopar

If you are keen on originality, keep all connections clean, tight, and check them often. Keep original spec alt.
If you are keen on reliability, disconnect the ammeter, replace with volt gauge, and do the alt to battery bypass to remove load from the B/H connector. And headlight relays.
The B/H connector is the weakest link, but an ammeter induced smoke show is not uncommon.

[Skdmark]

I'll be facing this decision before too long...

https://www.hemmings.com/stories/2021/10/01/how-and-why-to-replace-an-ammeter-with-a-voltmeter-in-a-vintage-mopar

My   
Run the bypass wire and swap the ammeter for a voltmeter. Both can be done very stealthy and keep it looking OEM.

[7E-Bodies]

@Skdmark that's the direction I'm leaning. Although I'm a purist with this project, I'd hate to watch it burn to the ground. (Especially after fighting many car fires on a local volunteer department and seeing how quickly they are destroyed). I've bought all of the M&H harnesses from Y1 and they're ready to install when I reach that point soon. Can you reply with some more info? Links to the voltmeter replacement? Maybe a sketch of the wiring bypass? Thanks in advance.

[Skdmark]

@7E-Bodies

Bypass wire routing:
https://forum.e-bodies.org/electrical-and-audio/11/alternator-bypass-wire-routing/18432/

I prefer the "front route"

Either pick up a pre-fab bypass wire from crackedback or make your own.

1. Wrap the bypass wire in OEM loom wrap to add some camouflage. Will look just like your M&H harnesses. If the insulation on your terminal connectors are not black, you can cover them some black shrink wrap tubing.

2. From the alternator, at a low angle get the wire over to the passenger side inner fender, then turn towards the front yoke and route it under the horns and around the bottom of the washer bottle.

3. Pass the wire up through the opening in the radiator yoke behind the headlight buckets and have it follow along behind the headlight harness across the radiator to the driver's side. The wire tabs are big enough to hold both wires.

4. Once behind the driver's side headlight bucket pass it back through the radiator yoke and run it either behind the battery or under the battery tray over to the starter relay.

[Skdmark]

Voltmeter
Use the Sunpro voltmeter conversion.

Here is great post on it. I did not have to trim the OEM gauge plate. It can bolt on. See the second thread below.
https://forum.e-bodies.org/interior/6/voltage-gauge-for-cuda-rallye-dash/685/

Start at reply 36 and onward for the conversion I also did using the Sunpro gauge ($11 from walmart.com).
You can keep the OEM face and graft your OEM needle on to the gauge. Cosmetically no different when installed.
https://forum.e-bodies.org/your-restoration-project-roseville-moparts/10/71-barracuda-ev2-h5xv/17032/msg263371#msg263371

[7E-Bodies]

Amazing replies! Thank you all! Now I just have to figure out how to save all this to refer to when it's time. For now, I guess it's copy paste to word document and save in my project electrical file.

[Skdmark]

Here is a way to "bookmark" threads from this forum.
https://forum.e-bodies.org/forum-help-and-suggestions/14/how-to-save-threads/22689/msg272737#msg272737

[72RoadRunnerGTX]

And the myth of the spontaneously combusting ammeter is perpetuated once again. By far the most factually inaccurate article I've read promoting voltmeter conversions to date.

[70rag383]

And the myth of the spontaneously combusting ammeter is perpetuated once again. By far the most factually inaccurate article I've read promoting voltmeter conversions to date.

Agreed, it's not the ammeter, it's the bulkhead connections that are the problem.

[DeathProofCuda]

And the myth of the spontaneously combusting ammeter is perpetuated once again. By far the most factually inaccurate article I've read promoting voltmeter conversions to date.

Agreed, it's not the ammeter, it's the bulkhead connections that are the problem.

Ammeters cause their share of issues, often due to failures of the crappy insulation material on the back of the gauge.  When I bought my current Cuda back in '88 the ammeter had already been bypassed due to a failure of that insulation that caused a short to the ammeter gauge body, frying the fusible link.  I replaced the insulator material with something a bit more robust, reconnected the ammeter, and haven't had an issue with it since.

[Mr Lee]

And the myth of the spontaneously combusting ammeter is perpetuated once again. By far the most factually inaccurate article I've read promoting voltmeter conversions to date.

Agreed, it's not the ammeter, it's the bulkhead connections that are the problem.

Ammeters cause their share of issues, often due to failures of the crappy insulation material on the back of the gauge.  When I bought my current Cuda back in '88 the ammeter had already been bypassed due to a failure of that insulation that caused a short to the ammeter gauge body, frying the fusible link.  I replaced the insulator material with something a bit more robust, reconnected the ammeter, and haven't had an issue with it since.

I'll second that.  After seeing smoke coming out of my dash and seeing my cars life flashing before my eyes, this is what i found behind my volt gauge. (I swapped my ammeter for a volt gauge).
I was kicking myself for not seeing this when i put it together.  The hole in the paper gasket was too large and the electrical connection shorted out to the back of the gauge housing and burnt the wire to a crisp.




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[71vert340]

I agree with running a heavier gauge wire from the alternator and cleaning the bulkhead connections. An additional change that I made was to replace all my exterior lights with LEDs to decrease the current draw from the alternator and putting stress on the electrical system.
Terry W.