Idaho fish
Active Member
I am getting ready to order a wiring harness kit for my 68 barracuda. I am finding out I need to change from an ammeter to a voltmeter. How do I do that while keeping the stock gauge and have it read correctly
Ammeter to voltmeter conversion
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67Dart273
Well-Known Member
?? You can't really do that exactly, but there's a VERY old, VERY good thread on "converting."
Read the whole thread, it covers a lot of ground. I don't think the original Sunpro meter is available, there were other threads over the years on here about alternative meters. Sorry offhand I don't have that
Ammeter to Voltmeter...who does it?
Read the whole thread, it covers a lot of ground. I don't think the original Sunpro meter is available, there were other threads over the years on here about alternative meters. Sorry offhand I don't have that
Ammeter to Voltmeter...who does it?
slantsixdan
=..=
A good ammeter-to-voltmeter conversion can be done very cleanly without looking hacked. I strongly UNrecommend the hack-job "fix" proposed by the clowns at MAD Electrical; you can do much better. How much it costs depends on whether you do the work yourself or have it done for you. Redline Gauge Works or Williamsons can both do a stealth conversion of stock ammeter to voltmeter for "it must've come that way from the factory!" appearance as seen in the '62 Plymouth here (look closely at the instrument panel; the Alternator gauge now has a scale from 8 to 18 volts rather than the original D at the left and C at the right—and the oil pressure gauge is another never-offered-by-Chrysler item done by one of the gauge specialty houses).
For less money (but more work) you can just buy a Sunpro voltmeter, tear it apart, and mount the old ammeter face over it with excellent, clean results as shown here and here.
For less money (but more work) you can just buy a Sunpro voltmeter, tear it apart, and mount the old ammeter face over it with excellent, clean results as shown here and here.
Easy, Gentlemen. We all need your decades of experience and input. Both of you guys have contributed more knowledge than you would believe. I know I'm a bit crabby as I age, but both of you have helped me immensely. JMO.
BobW
Curmudgeon At Large
Who cares who's first? All out of medals.
There are still plenty of those Sunpro voltage gauges floating around. There are five Ebay sellers offering them right now. I got mine from this place, good price, fast and free shipping:
Sunpro 2" Voltmeter 12V Black / Black Bezel New CP8215 Authorized Distributor | eBay
Sunpro was acquired by Bosch several years ago, but it looks as if Bosch is offering the same or similar gauge still under the 8215 part number. It's available for less than the price shown at many resellers.
Electrical Voltmeter Automotive Gauge | Style Line 2”
Sunpro 2" Voltmeter 12V Black / Black Bezel New CP8215 Authorized Distributor | eBay
Sunpro was acquired by Bosch several years ago, but it looks as if Bosch is offering the same or similar gauge still under the 8215 part number. It's available for less than the price shown at many resellers.
Electrical Voltmeter Automotive Gauge | Style Line 2”
I just got off the phone with Williamson and he highly encouraged me to leave well enough alone if the wiring was good.....which it is. Interesting.
Who told you that and why do they think you need to do that?
If you are asking about keeping the Alternator (ammeter) gauge face plate but with a volt meter guts, that has been answered already above.
The guy at Williamson said they convert them and unless the customer wants the dial to actually read volts, they simply leave the ammeter face as is and do the conversion. The needle simply goes all the way to the left with key off and about two thicknesses to the right of center when running. He said in the roughly forty years they've been in business, they've never seen a fire caused "just" by the ammeter gauge. He said there was always something else that failed.
He also mentioned an article in Hot Rod magazine a while back that although he was grateful for, because he got lots of business from it, that he thought they unnecessarily scared people into thinking the ammeters are a bad thing. They actually like the Mopar system. He did say that if you planned on "much more" than a fully loaded stock vehicle could handle that you would probably want to do "something" then. Seemed like a pretty honest guy.
He also mentioned an article in Hot Rod magazine a while back that although he was grateful for, because he got lots of business from it, that he thought they unnecessarily scared people into thinking the ammeters are a bad thing. They actually like the Mopar system. He did say that if you planned on "much more" than a fully loaded stock vehicle could handle that you would probably want to do "something" then. Seemed like a pretty honest guy.
67Dart273
Well-Known Member
He is full of beans at least on some models, and so is Dan with his constant unrelenting criticism of MAD. The FACTS ARE that I have personally seen these fail. The photo at MAD of the melted ammeter face is hauntingly familiar in the years when guys put winches, driving lights, and snowplows on Dodge pickups through the 70's and 80's. My own 70RR was damaged--both the bulkhead terminals, and the ammeter.
The worst models are the newer stuff with plastic cluster housings.
1...The ammeter studs are not brazed or soldered to the shunt. They are "sorta" crimped. This means that the "sandwich" of the insulating washers---which can compress and come loose--sandwiched against the plastic housing through-hole---which can soften, compress, and come loose--then allows the loose stud to loosen connection between the terminal, the stud, and the ammeter shunt. From there it is a "snowball" Or maybe I should say "fireball."
2...The bulkhead connector failures are well documented on most models. The ONLY once not generally effected are the ?2? years or so which used the "through buss bars" through the bulkhead
3...Bulkhead terminals. These are essentially 1/4" flat spade "flag" terminals. As a former heating/ AC/ heat pump mechanic, I have fought these on a regular basis. "In my day" electric forced air furnaces used typically 5KW elements, which draw nominally 20-25A at 220-230V. That means that all of the interconnects in an electric furnace, which used to use these type terminals---see 25A on a very regular basis. THEY DO FAIL. I would guess that "in my day" I ran across perhaps 5 trouble calls per winter where an electric furnace had troubles of some sort surrounding the failure of these terminals. The point? THEY WERE NEVER DESIGNED to handle the output of an alternator
The worst models are the newer stuff with plastic cluster housings.
1...The ammeter studs are not brazed or soldered to the shunt. They are "sorta" crimped. This means that the "sandwich" of the insulating washers---which can compress and come loose--sandwiched against the plastic housing through-hole---which can soften, compress, and come loose--then allows the loose stud to loosen connection between the terminal, the stud, and the ammeter shunt. From there it is a "snowball" Or maybe I should say "fireball."
2...The bulkhead connector failures are well documented on most models. The ONLY once not generally effected are the ?2? years or so which used the "through buss bars" through the bulkhead
3...Bulkhead terminals. These are essentially 1/4" flat spade "flag" terminals. As a former heating/ AC/ heat pump mechanic, I have fought these on a regular basis. "In my day" electric forced air furnaces used typically 5KW elements, which draw nominally 20-25A at 220-230V. That means that all of the interconnects in an electric furnace, which used to use these type terminals---see 25A on a very regular basis. THEY DO FAIL. I would guess that "in my day" I ran across perhaps 5 trouble calls per winter where an electric furnace had troubles of some sort surrounding the failure of these terminals. The point? THEY WERE NEVER DESIGNED to handle the output of an alternator
The amp gauges aren't all the same. Some of them are pitiful in design. The one in a-body rally panel is well built. Its contact posts are molded or pressed into very rigid plastic. I've seen only 1 failed. The post that the needle pivots on fell out of the shunt bar.
And the 1/4" spade terminals are not used on the ammeter. They were used on the bulkhead connector. And we've seen them get overheated in any number of locations because they were crimped to wires that were just adaquate when new, and for various reasons got overloaded in subsquent years. So the point is there are weak areas in various points through the system.
Dimmer switch.
Headlight Switch
Bulkhead
The headlight connectors are wider, but only have 18 ga wire. Fine with 40 Watt lamps but not 55/60 Watt lamps.
On my '67 Barracuda, the accessory feed at the ignition switch showed heat damage. Why? Probably because an A/C was added around 1970.
Chrysler had some pretty good work arounds to split the loads when they knew they would be higher.
Dimmer switch.
Headlight Switch
Bulkhead
The headlight connectors are wider, but only have 18 ga wire. Fine with 40 Watt lamps but not 55/60 Watt lamps.
On my '67 Barracuda, the accessory feed at the ignition switch showed heat damage. Why? Probably because an A/C was added around 1970.
Chrysler had some pretty good work arounds to split the loads when they knew they would be higher.
Idaho fish
Active Member
Thanks for the info, I think I found my solution. On my 68 it has a blank gauge hole where the performance indicator is on my 67. I can put a voltmeter in there without having to mount on somewhere else
Watching and learning....
That is a very wise thing to do. I have replaced 5 a-body wiring harnesses, and each one showed some heat damage on the firewall "alternator in" and "battery out" contacts. On 2 of them, the plastic was melted to the point of allowing a short to the adjacent contacts. The problem can only get worse over time. Also, the new alternators and the newer remanufactured alternators have higher maximum current output, so, these days there can be even higher charging current through the firewall connector contacts, and those contacts are already over 50 years old. It could get even worse if high current lighting or audio were added with their power still routed through the original firewall connectors (not the right way to do it, but it happens).
As you know, the need to convert from an ammeter to a voltmeter is driven by removing charging current from the firewall connector contacts. As many others have posted, there are several ways to convert the dash ammeter to a dash voltmeter. I recently called Mr. Heater Box, and asked them if they offer a ammeter to voltmeter conversion. He replied that they don't currently, but they do have one under development, and it should be available within a few months. I have had good experience with Mr. Heater Box services and products.
Not your question, but I can't resist adding some thoughts you might find helpful, or annoying, or someone else might find annoying:
There are several ways (and even more opinions on) how to bypass the firewall connector to get charging current from the alternator to the battery. In any of those options, a new, properly sized charging wire should be run from the alternator to the battery, and the fusible link (or equivalent fuse or breaker) still needs to be there near the battery. To avoid problems, You should disconnect the original alternator wire from both the alternator and the firewall connector. Same for the battery charging wire, disconnect it from both the starter relay terminal and the firewall connector. Do not reuse those original wires/connections.
Another option, if you don't mind the appearance, it is easy to add an aftermarket voltmeter mounted under the dash, powered from an "accessory" power source. The voltmeter will read over 13 volts when the the battery is charging. Ammeter just sits there, doing nothing.
To get power to to the dash, I run a new, separate wire from the alternator (separate from the new battery charging wire), and route it through a bulkhead feedthrough that I install in the firewall. It is very convenient to connect that dash power to the "alternator" stud of the ammeter (where the original black dash harness wire connects to the ammeter stud), so that's where I make the connection. Leave the original black dash harness terminal connected to that stud, because that's how power gets routed everywhere. Some people add a fuse or circuit breaker in the dash input power line from the alternator. The new wire must be sized properly.
KitCarlson
Well-Known Member
Use something like this, charge your phone too. $13
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KC69Cuda
Well-Known Member
I never got around to posting a thread from when I did mine. I overhauled my cluster 2 years ago & swapped a SunPro voltmeter in place of the ammeter as part of doing some electrical system upgrades.
It took a bit of finesse & mods, but I overlaid the SunPro gauge [round] faceplate on top of the ammeter faceplate. The sunpro faceplate is a bit more glossy black, but I'm satisfied with my results. Not a job for a novice. Here's a few pics...
It took a bit of finesse & mods, but I overlaid the SunPro gauge [round] faceplate on top of the ammeter faceplate. The sunpro faceplate is a bit more glossy black, but I'm satisfied with my results. Not a job for a novice. Here's a few pics...
Just my personal opinion...
If I was to do a Ammeter to voltmeter swap I would cut the arm off the stock gauge and glue it to the voltmeter gauge. I would also use the stock face plate and tune the voltmeter so that at whatever normal charge voltage you have the needle is centered. If it is significantly to the right it is over voltaging significantly to the left and undercharging.
Another option would be to get a remote Ammeter that uses a magnetic pickup and put it on the battery feed.
Lastly if you do run a dedicated charge wire directly from the alternator to the battery post on the starter relay AND assuming your Alternator feed to the Ammeter and battery feed to the Ammeter wires are good and the connectors at the bulkhead are good, by leaving the stock wiring in place ( at alternator and starter post) you cut the current through each connector in half.
If I was to do a Ammeter to voltmeter swap I would cut the arm off the stock gauge and glue it to the voltmeter gauge. I would also use the stock face plate and tune the voltmeter so that at whatever normal charge voltage you have the needle is centered. If it is significantly to the right it is over voltaging significantly to the left and undercharging.
Another option would be to get a remote Ammeter that uses a magnetic pickup and put it on the battery feed.
Lastly if you do run a dedicated charge wire directly from the alternator to the battery post on the starter relay AND assuming your Alternator feed to the Ammeter and battery feed to the Ammeter wires are good and the connectors at the bulkhead are good, by leaving the stock wiring in place ( at alternator and starter post) you cut the current through each connector in half.
Still learning. My all stock '70 340 Swinger 340 needs some safe upgrades, while appearing stock. You electrical gurus rock. I'm familiar with installing wire bundles, and have an O'Scope, but stuffing a TF 408 in a stock wiring system ain't going to cut it. I've learned a ton of electrical information from all the members here. I bought a sheet of 4X8 plywood to make my own harness with upgraded wire gauge and connectors. More to follow.
Idaho fish
Active Member
That looks great, I will probably still use the blank hole for the voltmeter and leave the ammeter unhooked. But if I did do what you did it would allow me to put a tach in the blank hole.I will have to do some serious looking at it and study everyone's comments before I decide how to do it
If its stock then its fine. That system worked for 100 of thousands of cars. Add a relay circuit for the headlights. Why? because the original lamps were rated 40/40 Watt. Since the 70s replacements draw more. Bonus of using a relay harness is that reduces the maximum possible load through the R6 wire by 9 amps. I'd say the biggest issues are condition of wires and connectors. That most certainly includes the quality of the repair and replacement work. It also includes good wire routing and support. I, like many others, didn't give those last two much respect as young shade tree mechanic. But thats a big part of why wires and junctions survive long use without damage.
If you really want to do some reworking, again assuming stock loads, then copy one of the 'fleet' or 'heavy duty' wiring schemes. A parallel wiring is another approach, which is similar to the 'heavy duty' scheme used on 70s models with rear window defrost grid.
The voltmeter in the cigar lighter is OK for an occassional check. Check your year for where in the fusebox that is wired to. ;)
Sure don't want a slow drain! Thats exactly the type of thing that causes high battery draw and damages stuff!
Idaho fish
Active Member
I am going with a new wiring harness from classic industries, it is supposed to match up to the stock system except for the ammeter issue. Hopefully I will be able to figure it all out. Its a long term ground up project so I can take my time and study things out as I go
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