rdrman

When I bought my 74 the amp gage was not working. Replaced it with a voltage gage from a 78 or 79. Now I"m replacing my hoses for the vacuum system and have the dash apart. I tested the amp gage and to my surprise I found that it works after all ! Originaly I found the wires to it cut.Would you reinstall it or go with the voltage gage instead? Which in you opinion is more accurate,or provides more information.Anyone? Any preferances? :confused:

Ganey

The volt guage is better. It can show when the battery is bad. I don't have a strong preference. If you don't care about your clock, you could install both w/ voltage in clock position.

:cheers:

mrvette

Simple, voltmeter, easy choice, just make sure you jumper the ampmeter wires together or the alt will not charge...

GENE

rdrman

Never really thought of using both.Might be worth a try :cheers:

norvalwilhelm

A volt gage is best and a large #8 or #6 going directly from the alternator to the large battery wire on the starter.
Norval

flynhi

Norval, Do you recommmend a # 6 to the positive post on the volt gauge?
From the battery + or from where?

427V8

So would the volt gauge from a 78 fit into the amp meter spot in a '69? Or is surgury required?

norvalwilhelm

The most effective way for a charging system to charge is through a large direct wire to the battery positive post. The vet sends the charge through a number 10 wire to the amp gage on the dash then through another #10 wire to the battery. This is not the best idea. That #10 is very restrictive. New cars usually run a direct #6 or so directly from the alternator to the battery. No resistance. When I installed my 140 amp alternator they told me to run a #6 from the alternator to the positive post on the battery so the easiest way was to the heavy wire on the starter motor. Since I have a remote solenoid that has the large cable on one side I ran to this heavy starter battery wire on the positive side of the battery. There is no resistance with a #6. A number ten is only rated at 40 amps max so how can a 100 amp alternator expect to send this charge through that small a wire.The resistance is too high. This move does render the ammeter usless.
Norval

73Ken73

The volt gauge requires only a small wire since it has a high impediance and it really doesn't pull any current. I agree with norvalwilhelh about the wire to the alternator and battery.

rdrman

Had to modifie the back as one has the terminals in a vertical arangment while the other one was horizontal, really an easy job as long you take your time to drill the 2 holes correctly and reuse the insulaters :cheers:

flynhi

So, Norval,
If I have a 95 amp alternator with an OE wire harness and an amp gauge, I cannot get the juice to the battery or users (such as headlights) due to the 10 gauge wire choking it down?

And a 6 gauge wire from alt to starter batt lead terminal will allow full 95 amps to get to the battery?

Thanks

mrvette

UHH, guys, you all seem to be forgetting how the car is harnessed up, the alt goes to the tiepoint on the fender, horn relay...that wire should be #8 or better... now from that point the wire going to the battery at the starter can be #10 easy...as it's just a charge wire, and in fact has a fuse link in it...
gotta take the harness apart to see it...too boot on my '72 the harness has a splice to thinner hi temp insulated wire, due to exhaust....you really don't want to dump all that much power all at once into a battery anyway, causes problems if the battery is weak/failed....
now off the horn relay is pulled about 5-6 other stock factory wires....going everywhere, and on MY car, even more for amps, computer FI, etc....
my engine cooling fan goes direct to my alternator, through the relay of course...
the voltmeter should be run to instrumentation ground, and to the two wires from the ampmeter, that are connected together, so that's in effect 2 wires there...
to positive voltmeter....
GM wiring diagrams are hard to follow in recuced sizes we get, OH for a D size drawing....damn eyes, can't see for poopie anymore....;-(((

GENE