hey i got a amp gauge for my 71 chevelle where do i connect the possitive and negative wire for the gauge????

It would be connected somewhere in the vicinity of the Electrical forum.

You may want to use a volts gage rather than an amp gage.

The ammeters need to run off of a shunt, somewhere close to the battery. Basically, it installs in the hot wire that goes to the battery from the main harness, which supplies power to all the car's electrical, and also charges the battery from the alternator. Make sure to run a big enough wire to handle the total amps your car could potentially use, i.e. lights, stereo, a/c system, electric fans, etc. all at once, without overheating and becoming a fire hazard. This is one reason most people use a volt meter, much easier to hook up, and safer too. Good luck.

The ammeters need to run off of a shunt, somewhere close to the battery. Basically, it installs in the hot wire that goes to the battery from the main harness, which supplies power to all the car's electrical, and also charges the battery from the alternator. Make sure to run a big enough wire to handle the total amps your car could potentially use, i.e. lights, stereo, a/c system, electric fans, etc. all at once, without overheating and becoming a fire hazard. This is one reason most people use a volt meter, much easier to hook up, and safer too. Good luck.

"Factory" ammeters, which are really a center-zero voltmeter, measure the voltage dropped across a shunt resistor (straight piece of wire from the battery + terminal to the horn relay in this case). They typically only require 100 milliamps of current to drive them to either "+" or "-" full scale and thus are a very safe way of representing the charging/discharging current. True ammeters carry the full charging/discharging current which could be as high as 61-63 amperes in an early Chevelle. Having this much current floating around under the dash of one of our "pride and joy" Chevelles is a fire waiting to happen. So, in lieu of a factory ammeter, a voltmeter is the safest bet and conveys a more correct (by today's standards) representation of the charging system health.

Hope this helps!

Not positive about a 71 but on a 70 it would be across the the junction block and the horn relay. The junction block is mounted on the rad support behind the battery. The horn relay on the other side of the rad support by the voltage reg. Don't remember if they changed the horn relay location in 71 or 72. Anyway that's how it should be wired then it will show if the bat is supplying power, discharge, or the alt, charge.
EDIT:
As Dave said it's not really an ammeter, it's a volt meter. The voltage drop across the jucntion block and the horn relay is what it is showing. The junction block is the main connection to the electrical system for the battery. The horn relay is the main connection to the electrical system for the alt. By measuring the the voltage drop across the wire that connects the two you can determine if the battery is supplying power or being charged or at 0 the alt is handling all the electrical needs.

hey i got a amp gauge for my 71 chevelle where do i connect the possitive and negative wire for the gauge????
Is it a factory amp gauge or a aftermarket gauge? If its a aftermarket gauge, don't use it, get a volt meter.