The Stovebolt Site Forums The Shop Area The Electrical Bay Replacing amp gauge with voltage gauge question - need some ideas

Got my new wiring harness installed on my 55.2 12 volt and it feels like a new truck. The amperere gauge is wired up, but I don't think it's working (basing that upon a bunch of articles I've read) - there is very little to no movement in the needle even when turning on all the lights and using the cig lighter. I'm guessing it's because the gauge was not rated to handle the newer alternators (I have a 1978 small block installed) and so I want to put in a voltage meter - BUT I'M TRYING TO FIND SOMETHING ORIGINALish... I have the round dial gauges so I would like to stay similar.

Any ideas on the best way to try to keep my original look of the gauges but with a voltage meter?

Here is my dash now: https://flic.kr/p/u7HK7j

Not the same gauge but I am still running an original amp gauge in my 59 chevy truck. I have a 283 with a later alternator and my old gauge works fine. Did your gauge work before your swap? Did you wire it correctly? You should get movement when you rev your engine.

It was not hooked up with the old wiring, so I don't know if it worked or not. I read a tech tip on stovebolt - http://www.stovebolt.com/techtips/electrical/voltmeter/

So I'm thinking my modern alternator is too much for the old amp gauge, but I really have no idea.

I get little to no movement out of the gauge. It's wired per the instructions from Bill at Hot Rod Wires.

Not knowing what the original output VS. the new alt output it is hard to say what might happen or has happened.
If your new alternator is still running through the old amp meter and old wiring to charge the battery and provide current for loads you can have serious issues.
First to fail is the weak point of the whole circuit the fine wire that moves the needle in the amp gauge itself. This would be seen by no needle movement.
If the current is to much higher then original then the next to fail would be the old main wire or the shunt in the amp meter. This would result in draining the battery till out of juice.

If you want to keep the vintage look then the old amp meter needs the new shunt to handle the extra current plus a re-lable on the + - current level on the meter face.
If you desire a volt meter in place of the vintage amp meter then the amp meter needs removed with the two leads removed from it tied together to bypass the amp meter. These could be placed on the positive post of the volt meter to provide its source for sensing.
Or in today's age of digital an amp/voltage meter all in one could be placed in the cab to view both amps and volts on one display.

No mater what your choice, determine old VS. new currents. Do this to see if new main wire is needed and what is needed for an amp gauge.

Thanks 48x.

The alternator is the same one on the truck since it was built in the 1980's (truck is not all original). I have faith in the new wiring harness that I just put on from Hot Rod Wires. I'm going to see if I can find a retro looking voltage gauge.

Your gauges are they standard round Stewart Warner diameter?
Or some other size?
Either way should not be hard to find a vintage VM gauge or a retro looking replacement.

A couple years back when I was rebuilding my Land Cruiser panel I had a catalog with a nice looking (vintage chevy style) VM gauge that had a small blue (dim-able) barely noticeable digital amp reading in the bottom center. Best of both worlds, today's digital world meets vintage iron.

This is what I did with my '38. I got the 6v voltmeter and the stem light on ebay (sticker shock warning!!!). I left the ammeter in the dash. I use a 12v bulb in the stem light to keep it from being too bright (I have the OEM 6v system).

It's a good idea to abandon amp gauge. They are fire starters. Volt meter very easy to install.
As far as originalish. It's all about the diameter of gauge, color of face and sweep.
I do not know if you are wanting to put gauge in original position or a period looking hang down. Putting into the gauge cluster will be very hard. Probably about a 90 deg sweep gauge positioned so that needle sweeps old markings.
Got $850?
http://www.tuckersparts.com/Tach-Force-Gauge-Cluster-TF01B.html
For hang down: Auto Meter has several styles that will look good: "Old Tyme Black", "Traditional Chrome", etc. or a Ebay original SW working gauge. Who ever looks at an amp or volt meter? When battery goes dead you will know it. Then check alternator output and go from there. Carry a cell phone and credit card.

I'm running round gauges on my 55.2. https://flic.kr/p/u7HK7j

I may reach out to Bob's speedometer and see if they can "make" a voltage gauge using the housing on my amp gauge. In the meantime I'm going to pick up an average looking one for $20 from my FLAPS.

I was typing when you posted. HOLY COW!!! I was thinking Chevy. It's always good to say you have a GMC!!! Did not see pic. I had a 56 GMC. Very easy to find gauge to fit. No need for expensive custom.$$$$$$$$$$$
They sell a gauge face kit, you can possibly re-face a new gauge with correct SWEEP. Use the amp face on a volt gauge.
The GMC gauges are standard diameter. They can be taken apart.

A Hot Rod Wires harness is not made for an ammeter. To use it you will need to run a supply line to it and back. If you hooked the voltmeter wire to it, it is not going to read amps.

And by the way, I have never heard of a fire caused by an ammeter. Millions of vehicles ran millions of miles with them. I'm running a stock one on my Suburban with an alternator and an after market one on my yard dog with alternator.

A voltmeter is connected red wire to positive side of the battery, minus side to the negative side of the battery. (or equiv)

An ammeter is connected totally different with one wire from the positive side of the battery, thru the meter, then the second terminal to the alternator. There is no negative in that scenario.
Even if your ammeter has a + and - terminal. Its ALL positive.

Put your caliper on the back can of the gauge and measure. Or measure across the hole it came out of.
2 1/16 or 2 5/8.

I ran the wires for the ammeter separately from the harness, with the instructions provided by Bill from hot rod wires. One wire from the threaded terminal on the alternator, one from the positive side of the starter. Both lines have an in-line fuse.

Gauge is 2 1/16

Going to buy an aftermarket voltage gauge for now.

Check out autometer.com
should be one very close to your original look.

Each to his own, I know some people like voltmeters over ammeters, and I respect that. I don't want to start a war on this. So this is just one person's opinion:

1. I have had several alternators with my ammeter (1957 Chevy truck), they all worked fine. Assuming it works, the ammeter just measures what is there. Your alternator should be outputting withing the range of the ammeter's capability.

2. I like the ammeter because it shows current, charging or discharging, right away. It is an easy visual to determine the state of your charging system.

3. If the ammeter is wired correctly, and showing minimal deflection, is it possible the alternator is defective or not wired correctly.

Again, voltmeters are some people's preference for a variety of reasons. But I do know an ammeter should work in your scenario if you want that instrument.
don

We have all gotten "wound up" from time to time about ammeters and voltmeters. As I said earlier they are a silly, un-necessary gauge. We all think we have to have one. We don't. Most people do not watch it enough to spot anything soon enough. It's not like oil pressure or water temp. It won't damage anything if your alternator is not charging or the battery starts to die. When my batteries get low or go dead, I never have noticed ahead of time and most of you have not either. The ammeter does run high current and uses larger wire because of that. If it's all installed correctly and wire never chafes, no problem. I recommend a volt meter because it gives all the info you need to ignore and is actually a little safer. There are stories all over the place about burning wires/insulation and fires from ammeters. Maybe they are all liars. MAD electronics and Ron Francis advise against. I don't care how many times a person stood out in a lightning storm and didn't get hit or how many ammeters they have. Many auto Co.'s switched to volt meters in the 60's/70's. Their electrical engineers must have thought the Voltmeter would be adequate for monitoring charge and condition. It is a small issue here, no one has said his ammeter won't work, they do work, poster has it all set up, he's happy. It is great to stay "original" if you must. The idiot light actually was the best idea because you could not miss that. If you are a gauge watcher, you just hate idiot lights. You need to see a needle and precisely calculate the charging system condition every mile. Meanwhile, you run out of gas.

I'm amazed that millions of vehicles from the 1920's, 30's, 40's and 50's didn't self destruct, since "ammeters are fire starters". Incorrect, sloppy wiring by people who don't have any business fooling with electricity is what starts fires, not the choice of "ammeter or voltmeter"!
Jerry

OK bash the "fire starter" metaphor. Forget everything else I said. That's fair.

Wasn't trying to start a war here. When pondering the usefulness of the ammeter vs. voltage gauge, seems logic points that that voltage gauge has a slight advantage, but both can serve a purpose.

My goal with the truck is to keep the gauges looking as original as possible, but still having them work for safety reasons. I bought a $25 voltage gauge from my FLAPS and took it apart in hopes I could repaint it and put it in one of my old round gauge bodies; but no dice, the new gauge parts are way too deep and it won't fit.

I'm going to contact Bob's speedometer to see what they have on the shelf that may work. Now I'm trying to figure out how to get my coolant temp gauge to work.

No war here, just a "police action", advisors on the ground, training mission.

Smiling, I like both and each can serve a good purpose, but for every day use Volt is likely best choice.

A couple of interesting links (OK I know it is a from a foreign auto but I enjoyed working/driving these 30 years back)

http://mgaguru.com/mgtech/electric/et220.htm
http://mgaguru.com/mgtech/electric/et221.htm

Data applies to most any old amp or volt meter.