Volt meter vs. amp meter & 1 wire alternators

[mjhcobra]

I am about to put the dash together and find that this is a hot topic. I want the original look of the amp meter, but don't want flames under the dash.

I also want to use an external voltage regulator again for the original look, but I see lots of single wire alternators.

I currently have the original Smith gauges with the amp meter.

what do you guys suggest?

[Ron61]

Personally I used the volt meter as I like them more than an amp gage. But I am also not interested in making my cars look as original as possible. You could always use the amp gage and just not wire it but I think that would mess up your attempt to make the dash look original. I used a 100 Amp alternator, again not original looking, and didn't go with the one wire type. Either way, you will have a good looking dash and should be able to make the rest look close to original. Good luck and I hope that everything works out the way you want it to.

Ron

[RICK LAKE]

mjhcobra MJ I have gone to the Volt meter. SW gauges has the match in a classic chrome ring and black backing with white needle. I don't like the idea of running 100 amps through a 60 amp gauge and having to rely on small plastic insolators to protect the whole car. I am using the PAperformace setup Heavier wiring, with a master fuseable link, regulator and complete easy instructions on how to install. If you are not running alot of power ideas the 70 amp is fine for most cars. I have 2 fuel pumps, 3 cooling fans for motor, 2 for other locations. FI system and MSD. Mt gauge is in the middle of all this power useage and gets hot. Voltmeter just taps into the charging system. You have 3 wires to install to gauge 1 power from anywhere there is a battery hot wire, 1 for ground, the other is for dash lighting. Just make sure of good connections and having a clean ground to the external regulator. I hooked my charging cable to my starter soleniod on the battery side. ONly ran it for 2 minutes found no problems. reading about 13.9 volts. Rick L.

[Blas]

Mjhcobra,
They make a replacement Volt Meter that matches the original AMP Meter for the Smiths Gauges. It blends right in seamlessly. I have a few complete sets of extra gauges at the house but no Volt Meters or I would attach a photo. Here is one source to purchase one, you have many supplier choices.
VOLT METER (52MM) PART #ABV2220-07C WWW.GAUGEGUYS.COM
If properly installed, the AMP meter will serve you well. Both gauge types have their pros and cons. A properly installed master fuse, CB or fusible link will protect your electrical system. From what I have seen, your choice in the style of crimped wire end connectors will be the weakest point of any non-factory wiring installation. If you use those wire end connectors with the blue, red or yellow plastic tips over the crimps that are commonly available, even with the proper tool, they have often been the source of many problems. Why? You can’t SEE the final crimp…And the colored plastic ends are more wire gauge indicators then replacements for stiff heat shrink tubing. The more expensive crimp on wire connectors require a special tool to properly install. Usually $50 to $150 just for the crimping tool. But they have two sets of fingers, one that attaches to the wire making the circuit and the other set of fingers wrapping around the wire insulation. Add to that a heavy gauge heat shrink tubing and we’re talking “Space Shuttle” quality connectors.

[mjhcobra]

Originally Posted by RICK LAKE

mjhcobra MJ I have gone to the Volt meter. SW gauges has the match in a classic chrome ring and black backing with white needle. I don't like the idea of running 100 amps through a 60 amp gauge and having to rely on small plastic insolators to protect the whole car. I am using the PAperformace setup Heavier wiring, with a master fuseable link, regulator and complete easy instructions on how to install. If you are not running alot of power ideas the 70 amp is fine for most cars. I have 2 fuel pumps, 3 cooling fans for motor, 2 for other locations. FI system and MSD. Mt gauge is in the middle of all this power useage and gets hot. Voltmeter just taps into the charging system. You have 3 wires to install to gauge 1 power from anywhere there is a battery hot wire, 1 for ground, the other is for dash lighting. Just make sure of good connections and having a clean ground to the external regulator. I hooked my charging cable to my starter soleniod on the battery side. ONly ran it for 2 minutes found no problems. reading about 13.9 volts. Rick L.

Sounds like the simple solution, I am just have to going to get past the look of the volt meter. I am running 1 fuel pump, 1 to 3 fans for the engine, and maybe another fan for the driver-that's it. Maybe I can get away with a 70 +/- amp alternator but I don't want to shortcut myself in this department.

[Blas]

AMP Meter gauge wiring is very simple. All of the cars power users should have their power routed thru the AMP Meter, if not, you won't be getting a true reading on the gauge. One large wire in and one large wire out of the gauge (excluding lighting)and if you install the in & out wires backwards, the gauge reads backwards. i.e. Headlights "use" power not "make" power - the needle should move towards negative when the lights are turned on.
Regarding the alternator sizing, Do you have any big power users car? Your cooling fans are your biggest users, then headlights, parking lights, etc. The MSD box uses very little power, the fuel pump (if electric) usually between 2 and 4 Amps (i.e. Holley red-blue-black) Most wiring systems on these cars are not even sized for 100Amp service. Even on factory built cars.
3 fans for engine cooling? Check their Amp usage...progressive activation I assume?

[madmaxx]

The amp meter is a Lucas not a Smith. Always a good conversation piece to explain why the Lucas is there and not a Smith. I have the Lucas amp meter and love it, if wired properly you will not have any issues!!!!

[mjhcobra]

You are right, it is made by Lucas. How do you properly wire it? It seems that the volt meter is simpler and safer, especially with a higher rated alternator around 100 amps.

[madmaxx]

Blas is dead on, last I read was SPF wiring is sized for 50 amps.

[mjhcobra]

The trick is going to make sure the harness I get is built this way for an amp meter. I am looking at a Ron Francis kit and they are anti amp meters and use a single wire alternator. I have sent them my car specs and am waiting for a response to see if they can make one this way. If not, on to the next guy.
Any thoughts on the single wire alternator or harness manufacturer?

[mjhcobra]

Ron Francis said no way on the amp meter-my assumption is that the rest of the harness makers agree due to the gauge not being able to register more than a 50 amp charge. Seems stupid unless I use a 50 amp alternator, which again will not work. Final decision - 100 to 125 amp alternator with volt meter.

Still trying to decide on the single wire vs external regulator - any pros or cons????????

[DAVID GAGNARD]

Originally Posted by mjhcobra

Ron Francis said no way on the amp meter-my assumption is that the rest of the harness makers agree due to the gauge not being able to register more than a 50 amp charge. Seems stupid unless I use a 50 amp alternator, which again will not work. Final decision - 100 to 125 amp alternator with volt meter.

Still trying to decide on the single wire vs external regulator - any pros or cons????????

my 2 cars are both 65 Mustangs,street car and a race car, I use a volt gauge on both with the "old style" Ford alternator converted to a one-wire unit......Simple $40.00 conversion, takes about 1 minute and you only have one wire from the alternator to the battery side of the starter seloniod,clean and simple....the way I like it, simple is always better for me....

Personal prefrence is a volt gauge, accurately tells you what your alternator is doing or not doing...I don't worry about the amps, just make sure your alternator is not overloaded amp wise.....I would add up all the amp useage your car could pull at any given time and use an alternator that can supply that + 40%........if your total amp useage would be 40 amps you should have a 56 amp alternator, a standard 60 amp Ford unit would be sufficent......

I run a standard 60 amp old style Ford unit on both car and never have had any problems......idle speed, volt meter shows 12 volts, 1,000 to 1,500 rpms or more, volt meter shows between 13 and 14 volts...

David

[mjhcobra]

Thanks David for the insight. I saw on a previous post where somebody added up all the power that are drawn on an alternator. I will use it as a guide if I can find it. I guess originality is second to safety on this issue.

[PANAVIA]

Better Bigger, Alternators mean you are not beating on the battery as much , if you take the car for longer cruises a 65A might work OK.

there are plenty of options in the 90-130A category these days.

If you use a high AMP alt remember to use a suitable BAT+ connection from the power output section of the ALT to the battery lug/post so you dont weld anything accidentally.

like 10GA or better.

Steve

[mjhcobra]

If bigger is always better is the main reason, then I get it, but there is such a thing as overkill. You start to suck HP away after 95 amps or so.

I don't see a difference in my Cobra and a 65 T-bird with the same motor but has accessories out the ass and a 55 amp alternator. Worked then, why not now?????

[DAVID GAGNARD]

Originally Posted by mjhcobra

If bigger is always better is the main reason, then I get it, but there is such a thing as overkill. You start to suck HP away after 95 amps or so.

I don't see a difference in my Cobra and a 65 T-bird with the same motor but has accessories out the ass and a 55 amp alternator. Worked then, why not now?????

As far as sucking HP, that's a not exactly right......an alternator will only supply amps to the battery as needed. If you are cruising down the highway with nothing on,so to speak, your battery drain would be your ignition system and fuel pump (assuming an electrical fuel pump), amp draw would be small, therefore the alternator would not be "working hard" to replenish your battery, the more electrical current used, the more amp draw on the alternator,hence the more required to turn the alternator.......

A battery in good condition, fully charged will not tax the alternator much, HP draw is estimated at 1 to 2 hp!!!!!!!!!!! A weak battery would require more from the alternator, estimates are 3 to 4 hp.....either way, you'll never notice this!!!!!!!!!!!!!

Years ago, I had a camp in the woods with no electricity, we used a gaint battery (from some sort of industrial machinery, took 2 people to carry it) for the 12volt lighting system we had. The battery would last a weekend if you were careful, got tired of hauling back and forth home to charge it, so I took a 70amp GM alternator and mounted it on a homemade frame with a 3hp Briggs lawnmower engine to turn it. It would easily charge up a dead auto battery with no problems, but the big battery would kill the 3 hp motor when it had been used for a weekend, swapped out to a 5hp Briggs and it would easily re-charge the big battery.... The industrial battery was about 3 times the size of a standard auto battery!!!!!!!!!!!!!!

I used that homemade battery charger for years and when I sold the camp, I gave it to the new owner.....

If you have a 55/60 amp alternator, it'll do the job, it'll just have to work harder for a longer time to do the job, and subsequently build up more heat in it doing its job.....start any car and put on the A/C and other accesories for a few minutes and then go put your hand on the alternator case, I've done it, it'll be soo hot, you will not be able to hold you hand on it for more than 2 or 3 seconds, the alternator is working hard....higher amp units have higher output/capacity and don't have to work as hard as long......

Either alternator will do, larger just does it with less effort.......

David

[mjhcobra]

What do you think about using the Lucas ammeter (50 amp rated) with a 55 amp alternator? Can you use a larger alternator with the Lucas ammeter?
Sounds like using an 80 amp alternator with a max demand load of 60 amps with a good battery should work with the Lucas amp gauge-just pushing it to the limits for those peak demands when the battery is dead and everything is on.

Tough decision for originality.

[DAVID GAGNARD]

Originally Posted by mjhcobra

What do you think about using the Lucas ammeter (50 amp rated) with a 55 amp alternator? Can you use a larger alternator with the Lucas ammeter?
Sounds like using an 80 amp alternator with a max demand load of 60 amps with a good battery should work with the Lucas amp gauge-just pushing it to the limits for those peak demands when the battery is dead and everything is on.

Tough decision for originality.

I don't use amp meters on my cars, so I can say anything about using amp meters......I just prefer a volt gauge......My "amp meter" is to turn on the headlights and see how bright they are then, rev it to 2,000rpms and see if they get brighter....

An 60 to 80 amp alternator should work fine and as long as your battery is good condition, you shouldn't have any problems....My battery is a 7 year old, yes 7 year old Optima and it'll spin my motor over all I need and then some.........

One thing I've always done and may have contributed to the Optima's long life is when I know I will not be using my car for 2 weeks or more (which is sometimes often) I disconnect the positive battery terminal........

You may want to go to a local alternator shop and run your thoughts by them, they're experts in the field...

David

[PANAVIA]

My rule of thumb ;

I use voltage gauges on anything that has a alternator, and AMP gauges with generator cars.

My .04 cents.

Steve

[trularin]

I agree with Dave.

I have the 3 wire Ford system @ 60 Amps.

There are a few times when the fan, headlights and everything else is on, the voltmeter shows 12V.

Just my $0.02 worth.