What should my ammeter read ?

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thenewguy65

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Aug 15, 2006

#1

• Aug 15, 2006

• #1

I have a 65 with 66 stock gauges. I noticed that whenever the bass in my stereo hits, the ammeter definitely jumps. It's not steady at all. Sounds like I need to upgrade the alternator but I was just curious what a "normal" reading was so I could recognize it when I saw it.

Also, Once, I was driving and when I went over some railroad tracks, the radio cut out but the car ran fine. The radio came right back on by itself. The car never hesistated. Any ideas ?

 

Great68

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Aug 15, 2006

#2

• Aug 15, 2006

• #2

Of course the ammeter is going to jump when the bass hits, your amplifier will be drawing more current which means your ammeter will measure that increase. Upgrading your alternator will not cause an ammeter to stop jumping.

 

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thenewguy65

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Well I am not sure what's going on. Before I changed the intake over, with the exact same stereo, it didn't seem to jump like it does now. I changed the intake over to a cast iron 4 barrel. I painted the intake. Any chance that's affecting my grounds ? I am just trying to figure out the difference since I changed the intake.

I did have to slide the alternator around to change some belts. I am pretty sure I put it back like it was.

 

67Dylan

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#4

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• #4

You can upgrade the alternator to either a 100A or the big 130A, not too big of a deal. IMO I'd add a cap... depends on how much power to what size to get; figure 1000W needs a 1 farad cap as a rule of thumb.

I'm not sure about the mustang ammeter gauge question; I'm on my first 65 that I bought not running. I can make an educated guess, but I'm sure others on here can help.

 

67Dylan

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.

 

SoCalCruising

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#6

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What should my ammeter read?
I like to give mine a steady diet of technical journals, but some let theirs read fiction. What a waste.

 

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mustangman70

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Aug 16, 2006

#7

• Aug 16, 2006

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With my my powermaster 130 amp

With the bass pounding it never got below 13.

Normal operation with out bass should be 14.5 i think

 

Great68

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#8

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mustangman70 said:

With my my powermaster 130 amp

With the bass pounding it never got below 13.

Normal operation with out bass should be 14.5 i think

Click to expand...

That's correct for a voltmeter, but thenewguy65 has an ammeter.

 

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mustangman70

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Ah yes...

I guess reading comprehension ownz me today lol

 

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66Runt

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#10

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• #10

SoCalCruising said:

What should my ammeter read?
I like to give mine a steady diet of technical journals, but some let theirs read fiction. What a waste.

Click to expand...

I've always thought technical journals were a bit "heady" for an ammeter. I prefer "Road & Track", or "Car and Driver". Now a volt meter could appreciate technical journals.

As to the jumping ammeter, Clean all alternator mounting points to clean metal. Make sure your grounds are clean metal to metal and tight. This includes the ground wires that hook to the radiator support and the firewall.
If you have any kind of decent audio amp chances are good your ammeter either didn't work correctly before, or you didn't notice the jump.
With the engine running the needle should point slightly off center towards charging.

Good luck,

Scott

 

dennis112

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May 15, 2005

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Aug 17, 2006

#11

• Aug 17, 2006

• #11

blkfrd said:

so I simply put a 5 watt resistor in the ammeter circuit to get the ammeter to behave.

Click to expand...

I wonder if this trick woul help a "lazy" ampmeter needle that virtually never moves?

 

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thenewguy65

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#12

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I will check my grounds. I didn't scrap the paint off part of the intake where the ground straps bolt down. That might be it. The battery is brand new. I will also check my alternator output at idle.

 

dennis112

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#13

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blkfrd said:

It would have the opposite effect. The 21 ohm 5 watt resistor was put in to limit current to the ammeter so that the needle would not deflect too much. You need to check connections or reduce resistance in the ammeter circuit. I always recommend a 3 amp fuse in the ammeter circuit to protect it from burning out. The '66 ammeter only takes about 1/2 amp to fully deflect as I recall testing it in a lab here at work.

Click to expand...

blkfrd, thank you for information.

 

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ForceFed70

That's why they call it "dope"

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Aug 17, 2006

#14

• Aug 17, 2006

• #14

The ammeter guage tells you how much power the alternator is sending to the battery/car. When the bass hits, the alternator must send more power which would result in the needle jumping. To me it sounds like the ammeter guage is working like it's supposed to.

Don't get a stiffening capacitor. The money is much better spent on upgrading the battery or charging system.

 

67Dylan

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#15

• Aug 17, 2006

• #15

How much RMS is the stereo/amp rated at and what brand/model of amp? Any other electrical upgrades? I see a lot of information given regarding 'charging system' upgrades but w/out the needed information it's all uselsess.

Alternator upgrades & stiffening cap additions are helpful in the right situation. If you are really behind on the current demands the upgraded alternator is your best bet. If it is just a little dimming of say the headlights or slight fluctuations of the ammeter then the cap will help. Upgrading the battery; useless unless you plan on listening to the stereo for lengths of time w/the car off. If you're not going to do that, don't waste your money.