What I would do is (1) take off the positive batt cable from its batt post. (2) take off the heavy red/black wires/ring terminals from the ammeter studs in the ralley dash and connect them all securely together to each other with a small bolt/nut thru the ring terminals. (3) back at the battery (with everything in the car shut off incl ign) see if you have any amperage draw on your meter in series between the batt positive cable and the batt positive post (meter on low amps scale). If NO draw (eng off), hook the cable back onto the post & then start it up with the ign key with your nose under the dash to immed check for continued smoking & shut it off if any smoking anywhere. if not smoking the (now isolated) ammeter/stud connections is the prob. If there IS a draw, dont start it up but dig in & find/fix the source of the improper draw first then see if the ammeter or elsewhere is bad (smoking).