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bad ammeter
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Author:  Bing Kunzig [ Thu Dec 09, 2004 10:50 am ]
Post subject:  bad ammeter
I'm convinced the ammeter in my 63 Valiant is defective. I am also aware of madelectrical's solution. Of course there are differences of opinion on this. I read where later model slant sixes had an ammeter with an external shunt which might alleviate the problem. If so, do I get one off a later model car or are new ones able to acommodate this situation?[/b]
Author:  Super6 [ Thu Dec 09, 2004 11:07 am ]
Post subject: 
The later shunt ammeter setup basically redered the ammeter useless, as power had a path of lesser resistance through the shunt wire, rather than through the ammeter.

IMO you best bet is to remove the ammeter completely, and install a voltmeter in its place. This eliminates the fire hazard of a full flow ammeter, and the voltmeter is a better indication of what is going on with your charging system.

$0.02

-S/6
Author:  Bing Kunzig [ Thu Dec 09, 2004 11:48 am ]
Post subject:  bad ammeter
If the ammeter is removed and replaced by a voltmeter do the wires that went to the ammeter connect to the voltmeter?
Author:  Super6 [ Thu Dec 09, 2004 12:26 pm ]
Post subject: 
Not in the same fashion. Basically an ammeter is wired in series to the alt output wire. A voltmeter gets wired in parallel to an ignition switched power source.

The easiest way to remove the ammeter wiring-wise, would be to bolt the two wires currently going to you ammeter together, and insulate the connection w/ shrink wrap. A better ammeter elimination would be to replace the entire alt output wire from the alt to the battery, as the factory wire is probably old, cracked, corroded, etc. anyway. It does not hurt to increase the gage size of the alt output wire either; in fact, it will usually help the charging system at lower rpm's.

The voltmeter will have a small gauge wire that needs to be connected to an ignition switched power source, and a ground wire. The gauge lighting for either gauge will remain basically the same, though the connectors will (most likely) be different. Overall, the wiring is not difficult. :)

-S/6
Author:  Guest [ Thu Dec 09, 2004 9:36 pm ]
Post subject: 
Or you can do what I did, read the charging system by idle and electrics. Basically if my lights dim I'm charging bad, if I don't have my lights on but my idle is highly changed by added load I know it's charging bad. Not scientific, but has worked for a year. I plan on getting a voltmeter soon, but you know how long soon can take at times :roll:

-Shivadart
Author:  Bing Kunzig [ Fri Dec 10, 2004 8:54 am ]
Post subject:  bad ammeter
I have the instructions provided by Madelectrical regarding the conversion to a voltmeter. It calls for two fusible links. What is a fusible link?
Author:  Super6 [ Fri Dec 10, 2004 10:02 am ]
Post subject: 
A fusible link is similar to a slow-blow fuse. They look like regaular wires, but usually have a tag or labeling on them stating "fusible link". If too much current is run through a fusible link for too long a time period, the fusible link blows to prevent damage to the electical circuit it is in.

Generally,

A regular fuse will blow as soon as it's amperage rating is exceeded.

A slow-blow fuse may handle slight over-current for a second or two before it blows.

A fuse link can handle over-current for longer periods (guess, but I'll say around 10 seconds--don't quote me there).

A little more info is located here:

http://www.autoshop101.com/trainmodules ... n/118.html

-S/6
Author:  SlantSixDan [ Fri Dec 10, 2004 10:09 am ]
Post subject: 
The "fire hazard" of an ammeter is grossly overstated (there's even a website out there that goes on and on about how unreliable the factory ammeter is, fire danger, etc. etc. blah blah blah).

The opposing view:

The original ammeter worked fine without causing a problem (or a fire) for 42 years; that's a pretty good indication that there's nothing the matter with the original design. Ammeters are more useful than voltmeters, for they give real-time indication of what's happening with the car's charging system. A voltmeter, on the other hand, just gives a general overview of the system voltage. Unless the voltmeter is a very expensive, precision-calibrated item, the difference between "OK" and "Uh-oh" is often not very large or easily discerned. And of course, the big disadvantage is that there's no clean way to put a voltmeter in place of the factory ammeter. IMO, hacked dashboard gauges look schlock.

I'd fix this car by swapping in a new or good used factory ammeter and be done with it.
Author:  Super6 [ Fri Dec 10, 2004 10:31 am ]
Post subject: 
I will respectfully disagree.

If you are worried about the dash, disconnect the ammeter and leave it in place. There are plenty of mounting options on older vehicles that do not involve butchering the dash.

I prefer a voltmeter because it will tell you exactly what your charging system is up to. Not charging? Voltmeter will show battery voltage (~12.5 instead of ~14 volts) and slowly show the drain. Overcharging? Voltmeter will be pegged, showing the over-voltage.

Whereas, an ammeter will show 'discharge' in a no charge situation, but will also show discharge when the system is heavily loaded and everything is working properly. In an over-charge situation, the ammeter will show "charge", but how much charge is unclear on every ammeter I have seen.

I have only seen one truck burn to the ground because of the ammeter, but one was enough for me. Why take the chance when a perfectly safe alternative to monitor your charging system exists?

-S/6
Author:  SlantSixDan [ Fri Dec 10, 2004 10:34 am ]
Post subject: 
I doubt the truck you saw burned was "due to the ammeter".

Could a fault have developed in the ammeter? Sure, no doubt. Would it cause a fire? Nope, not unless someone ignorantly replaced the fusible link(s) with a regular wire or did other boneheaded "fixes".

In-dash ammeters are no more or less safe than in-dash voltmeters
Author:  Bing Kunzig [ Fri Dec 10, 2004 12:45 pm ]
Post subject:  bad ammeter
Good feedback on both sides.I just installed an extra used ammeter and everything is ok-for now. My questions for Dan and everyone else is how does one determine if a used one is good, other than by installng it, and who would have a new one for a '63?
Author:  SlantSixDan [ Fri Dec 10, 2004 12:54 pm ]
Post subject: 
There are lots of sources for New Old Stock parts. Valley Vintage Auto Parts, Brad's NOS, Automobilia, Keep 'Em Rollin', Silke's, etc. You ought to run an Ebay search from time to time; a great many NOS parts are found there. There are also notoriously underhanded and overpriced sources (Mitchell Motor Parts is the prime offender) -- I avoid them. Spend the $6 (or whatever) on an occasional purchase of Hemmings Motor News, and look in the "Mopar parts and accessories for sale" section.
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