AMP vs Volts Hookup on 67

[dads1967dream]

I have a 1967 C10 that my dad bought when I was 5 years old. His dream was to fully restore this truck and ordered about everything in the catalogs to do so. Sadly he passed away a year ago so I decided to take on this challenge. I am currently putting in a new EZ Wiring kit and have a question about the amp vs volt meter. I have a 105amp alternator on the truck, is this too much for the amp meter to handle? If not is there anything special I need to do in hooking the cluster up, all gauges, no tach with mechanical oil Thank you in advance.

[michael bustamante]

there is a guy in the parts section that sells a kit cheap to convert the ammeter to a volt guage. that would be your best bet. i think it could handle your alt. just fine

[davepl]

I think you're fine. Our is not an ammeter in the sense that all the of the truck current flows through it to be measured. Our is more of a voltage differential indicator - how much more current (or less) there is at the alternator vs a remote point (normally the generator idiot light) in the circuit.

In two cases where I've added a large (>100A) alternator to an old car with an alternator the worst case has been the gauge pegged once or twice because the alternator was outputting a lot more than the gauge was calibrated for. But that doesn't mean there was any more current at the gauge or anything, and it wasn't getting hot, etc...

Again, not a real ammeter, so shouldn't matter. Just my advice, I wouldn't change a thing, and didn't when I put a 100A in my own truck with a factor ammeter.

You -might- want to consider upsizing the alternator output line. It's something like 12G and that's not enough to be carrying 100A. I'd run 4 or 6 or 8 as appropriate from the alternator to the junction, because that IS carrying all the output. But even that should mean a worst case of a hot wire when it's really working and some unwanted resistance.

Cool project by the way! Sounds like a lot of pressure, just keep making slow progress at it and it'll take care of itself. As long as you're always making a little progress each day... then a couple of years later it's done! That's how mine went anyway - years of slow progress.

[VetteVet]

If your original cluster was a gauge cluster You'll be fine and the ammeter will work just fine.
If your wiring does not have the alternator conversion wiring installed then it will not charge
but the conversion is easy.

If you have any problems, post in the electrical section and we'll help you out.

[davepl]

Dang, I said "How much more current" is present at one point in the circuit, but I meant voltage. If you've got more at the battery than at the alternator, for example, it'll read discharge I guess but it's not actually measuring current, just inferring it from the voltage present and what the implies about current flow.

So I understand it, anyway.

[RichardJ]

The Ammeter in these trucks is a real Ammeter.
Ammeters are sold in two configurations. All Ammeters use a SHUNT. An Ammeter can have in internal SHUNT or it can have an external SHUNT that you buy separately or you configure yourself using a little math.
The shunt and the Ammeter are in parallel so current flows through both at the same time. The difference is that 99% of the current flows through the shunt and 1% flows through the meter movement. Yes, the meter is a galvanometer or d'arsenval movement and you could call it a voltmeter, but when configured with a Shunt and calibrated in Amps, it is a Ammeter.

These trucks simply use an Ammeter that requires an external shunt. GM used existing wire in the harness to serve a dual purpose role.

Stewart Warner sells Ammeters in both configurations for automotive use. They used to sell Marine gauges and I think they were all for external shunt.

http://67-72chevytrucks.com/vboard/s...nt#post6853326

[dads1967dream]

Originally Posted by dads1967dream

I have a 1967 C10 that my dad bought when I was 5 years old. His dream was to fully restore this truck and ordered about everything in the catalogs to do so. Sadly he passed away a year ago so I decided to take on this challenge. I am currently putting in a new EZ Wiring kit and have a question about the amp vs volt meter. I have a 105amp alternator on the truck, is this too much for the amp meter to handle? If not is there anything special I need to do in hooking the cluster up, all gauges, no tach with mechanical oil Thank you in advance.

What is meant by alternator conversion? The kit came with an excitor wire that is hooked up along with a loop to the starter.

[davepl]

Yes, the meter is a galvanometer or d'arsenval movement and you could call it a voltmeter, but when configured with a Shunt and calibrated in Amps, it is a Ammeter.

We disagree on terminology only I think - I consider a "real" DC ammeter to be one that measures the actual current in the circuit across the internal shunt as the only current path. Your definition is broader. The proper definition probably only requires measurement and display regardless of how it's achieved (but I haven't looked yet!). Even the AC coil induction things are ammeters.

I think of our gauge more as showing the voltage potential to take a shortcut around the external shunt... but that's probably because I'm a software guy and not an engineer. I even went out with a voltmeter and tried it myself. I think our gauges are calibrated such that a 2V differential reads full charge/discharge, but that's just a guess from experimenting.

Two questions, since you seem to know yours stuff:

Where is the voltage divider (ie: the resistor) that splits it 1/99? Internal resistance in the meter itself?

Are there any implications to upsizing the alternator output feed? Since a heavier gauge wire might be appropriate for 100A alternator (stock is 12GA I think) wouldn't that reduce resistance in the external shunt and throw off the "calibration" of the ammeter? Or is it not a material difference?

[Big Kev-O]

The EZ wiring kit he is using comes configured for an alternator and volt meter. My EZ wiring kit came with an optional "alt bypass wire" that is to be used when the alternator goes over a certian amperage. If I remember correct they state to install the alt. bypass wire on any alt over 80 amps. The alt. bypass wire is a 10awg or 8awg wire that goes from the alternator output to the battery connection on the starter. I wired mine from the alternator output directly to the battery because it gets hot under the headers and didn't want another wire running to the starter. If you want the stock ammeter to work you will need fabricate the proper harness from scratch or utilize some of the factory wiring to integrate the stock setup.

If there is a conversion kit that changes the ammeter to a volt meter that would be the way to go and I would like to buy one.

[VetteVet]

Originally Posted by dads1967dream

What is meant by alternator conversion? The kit came with an excitor wire that is hooked up along with a loop to the starter.

The conversion would be from the stock externally regulated alternator to the internally regulated style. From your description the EZ kit has the correct wiring for the internally regulated style. The diagram Richard posted shows the easy method to do the conversion and as stated by Kev it would allow the use of the battery gauge (ammeter)

Originally Posted by Big Kev-O

The EZ wiring kit he is using comes configured for an alternator and volt meter. My EZ wiring kit came with an optional "alt bypass wire" that is to be used when the alternator goes over a certian amperage. If I remember correct they state to install the alt. bypass wire on any alt over 80 amps. The alt. bypass wire is a 10awg or 8awg wire that goes from the alternator output to the battery connection on the starter.

This sounds like the normal output wire from the alternator to the battery cable but you could run the output wire to the battery positive and get the same thing. It is a lot better to run the output wire to a separate junction and connect the output wire there along with a charging wire from the battery. The diagram in Richard's post shows this and it also shows the ammeter wires that would allow the ammeter to work.

I wired mine from the alternator output directly to the battery because it gets hot under the headers and didn't want another wire running to the starter. If you want the stock ammeter to work you will need fabricate the proper harness from scratch or utilize some of the factory wiring to integrate the stock setup.

If there is a conversion kit that changes the ammeter to a volt meter that would be the way to go and I would like to buy one.

There is no way to convert an ammeter to a voltmeter because the ammeter is wired positive only and the volt meter is wired positive and negative. Now if you mean the EZ harness has the negative and positive wires for the voltmeter, which you would have to install in place of the ammeter, which is what I think you meant, then the op would have to do as you said and fabricate the ammeter wiring as in the diagram.

[dads1967dream]

I cannot thank this forum enough for the education, my dad always broke things down like this. So, I think with the EZ wire kit I have the right setup so far- alternator bypass done, exciter done. On the back of the cluster there is a black/white and black across from each other which by following the circuit connects to the amp meter. These are my last two wires in the cluster to hook up. The instructions in the EZ wire kit tell me to route the 10 gauge solenoid pwr=red wire from the fuse panel to the amp meter and then from the other post of the amp meter to positive battery source. What do I do with wires in the cluster and do I need to splice into my starter solenoid wire that is already run to the starter?

[VetteVet]

Originally Posted by dads1967dream

I cannot thank this forum enough for the education, my dad always broke things down like this. So, I think with the EZ wire kit I have the right setup so far- alternator bypass done, exciter done. On the back of the cluster there is a black/white and black across from each other which by following the circuit connects to the amp meter. These are my last two wires in the cluster to hook up. The instructions in the EZ wire kit tell me to route the 10 gauge solenoid pwr=red wire from the fuse panel to the amp meter and then from the other post of the amp meter to positive battery source. What do I do with wires in the cluster and do I need to splice into my starter solenoid wire that is already run to the starter?

I don't think you need 10 gauge for the ammeter wires unless you have a pre 63 truck where all the power goes through the ampmeter (different animal)

It is really hard to advise you without knowing the schematics of the EZ kit.

The two wires you describe are the ammeter feed wires. The solid black one needs to run directly to the battery post or possibly to the starter solenoid with the main cable from the battery. The alternator output wire can not go there or the ammeter will not work. You see you must separate the alternator output from the battery positive and then connect the two with the wire called a shunt which is also the battery charging wire and the battery supply wire when the engine is not running. Richard explained this in the above post.

The black/white wire must be connected to the alternator output wire in order
for the ammeter to be able to measure the difference between the voltage potential between the alternator and the battery. If the battery voltage is less than the alternator output voltage the ammeter reads CHARGE and if the battery voltage is higher than the alternator output voltage the ammeter will read DISCHARGE.

It is possible that the main battery cable from battery positive to the solenoid can act like the shunt so the black white wire might go there and the solid black would go directly on the positive post or the junction on the right fender with the fusible link and the battery feed wire.

Where do they say to route the battery and alternator feed wires to the cab or fuse panel. Is it the 10 gauge wire from the solenoid to the fuse panel?
I have not wired one this way so I cannot confirm if it will work or not.

Here is a thread that will explain a lot about the battery gauge.

http://67-72chevytrucks.com/vboard/s...d.php?t=393139

[dads1967dream]

I think I get it. The EZ wire kit has basic setups, most show things but others do not or leave out wire setups the user may have. If I can use the the solenoid method, I will go that route. I have new blocks for the fenders and fusible links for each of those wires. I'm sure there are more questions coming as I go along and I thank everyone for the advice. My dad was a scope and radar mechanic on B-52s and others when I was young so we always received the answer after explanation in great detail, love that about this forum.

[RichardJ]

Copper wire has resistance. The length of the wire segment used for the Ammeter shunt, must have a specific resistance.
The Shunt is the segment of wire between the Junction Block near the battery and the spliced junction I have circled in ORANGE, in the wire loom. This is NOT the back of the Alternator. It is taped up inside the wire loom (harness).

One (1) side of the Ammeter connects to the shunt at this tapped up junction. The other of course at the Battery Junction Block.

Wire Gauge Resistance per foot
4 .000292
6 .000465
8 .000739
10 .00118
12 .00187
14 .00297
16 .00473

A wild guess, the Shunt segment is 5 ft.

5 X .00187 = .00935 Ohms, based on the guess of 5 feet.

The point is, if you use a longer wire the resistance will be higher, more current will flow through the gauge than the shunt and the gauge will read HIGH.
A larger than 12G wire will have a lower resistance and the gauge will read LOW.

The aftermarket harnesses are not set up for this original type Ammeter. It would make the harness more complicated for them and they'd have to hire 5 new phone techs to explain Ammeters to customers.

A voltmeter is much easier for them.
Saying >>the EZ harness has the negative and positive wires for the voltmeter,<< makes it sound even more complicated. The Neg wire is simply a ground wire.


>> pre 63 truck where all the power goes through the ampmeter << Same as what Chrysler used throughout the '60s. These were Ammeters with Internal Shunts.

[VetteVet]

Originally Posted by RichardJ

Copper wire has resistance. The length of the wire segment used for the Ammeter shunt, must have a specific resistance.
The Shunt is the segment of wire between the Junction Block near the battery and the spliced junction I have circled in ORANGE, in the wire loom. This is NOT the back of the Alternator. It is taped up inside the wire loom (harness).

One (1) side of the Ammeter connects to the shunt at this tapped up junction. The other of course at the Battery Junction Block.

Wire Gauge Resistance per foot
4 .000292
6 .000465
8 .000739
10 .00118
12 .00187
14 .00297
16 .00473

A wild guess, the Shunt segment is 5 ft.

5 X .00187 = .00935 Ohms, based on the guess of 5 feet.

The point is, if you use a longer wire the resistance will be higher, more current will flow through the gauge than the shunt and the gauge will read HIGH.
A larger than 12G wire will have a lower resistance and the gauge will read LOW.

The aftermarket harnesses are not set up for this original type Ammeter. It would make the harness more complicated for them and they'd have to hire 5 new phone techs to explain Ammeters to customers.

A voltmeter is much easier for them.
Saying >>the EZ harness has the negative and positive wires for the voltmeter,<< makes it sound even more complicated. The Neg wire is simply a ground wire.


>> pre 63 truck where all the power goes through the ampmeter << Same as what Chrysler used throughout the '60s. These were Ammeters with Internal Shunts.

Thank you Richard for the specs on the wiring and resistance. I have long thought that in order for the ammeter to work correctly, it must be wired like our diagrams show with the gauges per resistance that your diagram shows.

I've noticed that the pre-67 trucks were wired similarly but the black battery side wire is connected to the solenoid with the large battery positive cable.
The alternator side is connected to the horn relay junction which is similar to the 67-72 years. I've also had some members tell me that they have wired the ammeter wires like that and it worked.
Wiring the battery side to the solenoid would extend the SHUNT but the resistance of the large cable might be enough less to make up the difference.

It could be that EZ has done some experimenting with these trucks and have concluded that the ammeters will work as planned.

Your thoughts!

Here are the diagrams for the pre 67s.

The engine side top center my arrow is too small.




Inside the cab on the gauges shown on the right side with red arrow.

[dads1967dream]

I spoke with EZ wire this morning and they told me that with my 100amp alternator the amp meter setup will not work and will fry the harness. They said the amp meter cannot handle it. I feel very comfortable with what is being explained here. As mentioned above, if I put in a bar shunt, it would take 99% of the load and amp meter 1%. Has anyone used this method on a EZ wire system. I am thinking about going the volt meter route. Does anyone make a volt meter that fits the 67 cluster? Thanks again for all the great responses.

[70STOVEBOLT]

Originally Posted by dads1967dream

I spoke with EZ wire this morning and they told me that with my 100amp alternator the amp meter setup will not work and will fry the harness. They said the amp meter cannot handle it. I feel very comfortable with what is being explained here. As mentioned above, if I put in a bar shunt, it would take 99% of the load and amp meter 1%. Has anyone used this method on a EZ wire system. I am thinking about going the volt meter route. Does anyone make a volt meter that fits the 67 cluster? Thanks again for all the great responses.

Member TBONE1964 (Tom) sells voltmeters that have the 67-72 gauge face on them, contact him.

[davepl]

1% of a 63 amp load is 0.63A, and 1% of a 100A load is 1.0A. I'd be surprised if the difference between 0.63A and 1.0A would be enough to harm anything, but like I said, I'm a software guy only posing as an electrical guy...

[dennislbrooks]

ok, not trying to hijack this thread ( a very interesting thread for sure) but this thread has me thinking on what I am to do on a 46 with original ampmeter with a 12 volt one wire alternator - 63 amp.

I have no wiring to the cab and thot that I would run a 10 gauge from the battery thru a fuse then thru the ampmeter to the BAT on the igition switch. Is this correct or do I need another game plan.

[dads1967dream]

Ok new problem, dash lights work with 1st pull of headlight switch then go out when pulled all the way out. Thoughts?

[VetteVet]

Originally Posted by dennislbrooks

ok, not trying to hijack this thread ( a very interesting thread for sure) but this thread has me thinking on what I am to do on a 46 with original ampmeter with a 12 volt one wire alternator - 63 amp.

I have no wiring to the cab and thot that I would run a 10 gauge from the battery thru a fuse then thru the ampmeter to the BAT on the igition switch. Is this correct or do I need another game plan.

Well since it looked like we had Dads1967dream figured out I guess we won't mind fixing yours. your answer is pretty simple. Notice I said looked like LOL.

Here is the correct way to wire the pre 63 full power amp meter. You know the capacity of the meter is 60 amps so you should put a slightly smaller fusible link as shown on the main line to the amp meter to prevent possible overload of the meter. I doubt that you will push more than 60 amps through it but a fusible link would protect it just in case. I would put one on each side of the circuit to be safe.

Here is the circuit from the battery through the meter and back to the alternator. with power feeds off to the key and light switches etc.

[VetteVet]

Originally Posted by dads1967dream

Ok new problem, dash lights work with 1st pull of headlight switch then go out when pulled all the way out. Thoughts?

Check your parking and tail lights and see if the same thing happens. In 67 and maybe 68 the headlight switches were wired that way. You can put a jumper on the HL switch to have them come on.
Check this thread.

http://67-72chevytrucks.com/vboard/s...d.php?t=428826

[dads1967dream]

Does this apply to the dash lights as well. I have them wired together into 1 terminal but will jump them instead. I bought a new switch that I do not like, for some reason it has 3 positions out so I am back to the original. Also If I am looking at the switch right, it grounds off of being mounted or do I need to run a spade to the side turn down as well. Yes, I still am up in the air about the amp meter, just trying to be safe as I will be handing this to my son in a few years. Think I am going to try the shunt method and see what amperage I get. Thanks again

[VetteVet]

Originally Posted by dads1967dream

Does this apply to the dash lights as well. I have them wired together into 1 terminal but will jump them instead. I bought a new switch that I do not like, for some reason it has 3 positions out so I am back to the original. Also If I am looking at the switch right, it grounds off of being mounted or do I need to run a spade to the side turn down as well. Yes, I still am up in the air about the amp meter, just trying to be safe as I will be handing this to my son in a few years. Think I am going to try the shunt method and see what amperage I get. Thanks again

There is an orange wire that comes from the fuse panel to the headlight switch.
This wire is hot all the time and it feeds the brake light switch the dome light and the brown wires 9 (taillights) on the headlight switch. It also feeds the green wire coming from the headlight switch after going through the bright dim rheostat (variable resistor) to lighten or dim the dash lights.

This green wire goes to the fuse panel to the Pnl Lts fuse which feeds a gray wire to the cluster plug which is your dash lights.

The dash lights are separate from the tail lights although they are both fed from the same source (orange wire) It appears that the headlight switch does not make contact between the orange and green wires when it should. With the switch all the way out. Jumping the brown and green wire terminals should solve that or getting the stock switch will put you back to having the dash lights to work in either position. Then you can jump the green wire terminals with the brown wire terminal to get the tail lights on in both positions and also to have dash lights with the headlight or parking lights on. The 69 or newer switch will do that but I am not sure that the 67 harness will fit the newer switch, I don't think so. There's a picture in the thread I posted above of the stock switch and how to jump it.

Yes you need to have the switch body grounded in order for the dome light to work when you turn it all the way to the CW position. There should be a white wire in the harness which is the ground side wire for the dome light that will be grounded when you do that. It should light the dome light which is powered full time by the orange wire.

Here is the 69 switch (may be 68 too).



Here is the headlight switch wired with the brown,orange and green wires for the tail lights, the dash lights, and the white dome light ground.

[VetteVet]

Here is a picture of the stock 67 switch with the terminals and wire connections.
You would need to jumper the 927 and 929 terminals for the tail lights to work in both positions.



This picture and a wire description is in the thread I posted above. You might want to look at it.

http://67-72chevytrucks.com/vboard/s...d.php?t=428826

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