SPO2454 - Ammeter ?

[Moritz55]

Hello everyone... First of all I have learned a ton and used this site along with SCOF Site to help me understand and even make improvements on my MKIII. I have owned my SPF for 3months and have put 1000miles on! Love the car as I am the 2nd owner. It currently has 22k miles on it, MFG'd in 2007.

==> I can use some feedback/help on how my Ammeter behaves. Wondered if this is normal. Here is a pic of the Ammeter (with Master Pwr OFF)... See the needle is to the LEFT of "Zero".

CAR OFF observations:
1) With Master PWR OFF Ammeter rests slightly NEG.
2) With Master PWR ON Ammeter rests slightly NEG (same as with Master PWR OFF)
3) I checked for "Parasitic" type current draws... and have 0 m-ohm draw. So none measured.

For reference I added: NOTE: I have a 1 Wire Alternator (No VR) .
- Added New Alternator (Powermaster 105amp), the old one tested fine so I keep it as a spare. It's an identical replacement.
- Added a 8ga GND wire from the Alternator GND to the BAT-/Chassis frame.
- Added the Ammeter stabilizing "fix" : RED 12ga wire from ALT+ to BAT+.
- Added New RED Top Optima , use Battery tender with PWR Mstr OFF. Battery is always at 12.6-12.7v before starting .... so battery seems good.

==> The Ammeter has always been erratic to me, but wonder if this is normal?
Note: Car is wired so with Ignition "ON" , Headlights/Running Lights are always "ON".
1) Once car starts, Ammeter moves positive as depicted in pic 2 RED Line for a few mins. Then moves back to slightly NEG (like the first pic).
2) As I continue to drive, more than 5mins or so.. Ammeter drops ,more Neg to look like pic 3 RED Line, with Lights ON.
3) Then when Fans are ON and Lights ON needles drops further to look like pic4 RED Line.
I can drive 20-30mins and the needle stays negative or moves closer to pic 2 Red Line Left of "Zero"??

Is my Ammeter out of calibration because it doesn't rest at ZERO?
Is this NORMAL Behavior or something else going on?

Feedback suggestions are welcome.....

My Car is: SPO2454 Cobra MKII 427SC. It has a Roush427SR, 4BBL 770cfm Holley & TKO600 with MSD Disty & 6AL MSD box ...