That pesky amp gauge

[roadman5312]

I got to thinking about a 65 Comet I worked on last year. The main power wire did not attach to the gauge, it passed thru a loop on the back of the gauge( I'm trying to find a picture), I believe many early Fords were this way. I wonder if the Cuda?Challenger gauges could be simply modified to work this way.  Any ideas ?

[roadman5312]

This is the back of a 64 Comet amp gauge, no wires attach, the main power wire just goes thru the loop. I'm going to do some experimenting.

[RCCDrew]

Maybe put the face and needle of your ammeter on that gauge?

[roadman5312]

Well here's my first test. This is the back side of a 50 Chevy pickup gauge set. I made a loop and connected both sides of the amp meter. Then I ran a length of wire thru it and shorted that wire on the positive/neg sides of a battery briefly. The needle jumps  , . Now for accuracy  Ok I'm sure the loop will need to be made of a wide (3/8 maybe) piece of copper, which could probably be fashioned from a piece of copper tubing. I'm going to keep working on this, it could be a really inexpensive fix for all Mopars with the amp gauge problem.

[Cudaragtop]

Amp Clamp...
They come in AC and DC models. This is just one example but I'm guessing it's the same idea as your "Comet" amp gauge.

[ChallengerHK]

Personally, I'd still be concerned about passing all the current the car produces through the firewall and back out again. I think the voltmeter conversion is a better way to go 

[dodj]

In the years just before changing to voltmeters, Ford and GM amp gauges were a shunt arrangement. The ammeter circuit only carried about 5-10% of the total amperage. So, just to use round numbers, if the ammeter saw 1 amp, the actual system (shunt plus main) current was 10 amps.
Just something to keep in mind if your numbers seem off a lot when you are checking accuracy.

[roadman5312]

Thanks for the info dodj, I'm going to be pursuing this and trying to make it work. Also will be working on eliminating the main power wire bulkhead connector and running the wire straight thru.

[Bullitt-]

just a thought... I wonder if instead of just one wire through the loop if you made multiple passes(looping the wire) if you could achieve a more accurate reading.

[duodec]

Some years ago I asked about using an inductive ammeter gauge (SnapOn and others have sold them, and panel meters are also available) and adapting the mechanism to the Mopar gauge.  I don't recall getting much response but I'd really prefer to keep an ammeter, so still looking at doing that.  I found a 75 amp Cornwell inductive panel gauge but my rally ammeter is buried in storage so haven't been able to try anything yet.

The bulkhead connector can be bypassed easily enough to handle the power.  The Comet gauge looked interesting but I'd bet it doesn't have the capacity.  Inductive gauges and the shunt type seem to be available up to 150 amps pretty readily. 

[dodj]

just a thought... I wonder if instead of just one wire through the loop if you made multiple passes(looping the wire) if you could achieve a more accurate reading.

Looping the wire changes the ratio.
Two times the magnetic field equals two times the deflection of the inductive meter. If there was one amp flowing and there were two loops of wire, the gauge would read as if there was two amps flowing.

[roadman5312]

Basically to begin with I just want to see if I can make it work, your either charging or discharging. Then compare to a volt meter hooked up, turn on lights, A/C, etc and maybe fine tune. Just a spare time thing.

[brads70]

Interesting!