cal30_sniper
Member
Hello all,
I'm getting ready to swap in a roller V8 in place of my bare bones slant six, and will be upgrading the charging system to the 90A Magnum alternator to support electric fans and other power needs. While I've done charging system upgrades on GM products before (which is as simple as replacing the battery cables), I've never dealt with an ammeter or fusible link wiring before like the Mopars have.
I realize our cars have a shunted ammeter. My Factory Service Manual shows a 6GA cable between the positive battery post and the junction with the ignition/headlamp switch power, with a 10, 12, or 14GA wire continuing on from that junction to the alternator (mine should be a 14GA wire, as it has no power accessories or options). Somewhere between the battery and this power junction, are the two 20GA wires that come off and go through the bulkhead to the ammeter (which is the shunt type).
So now my questions:
1. If I run a new 4GA cable from the battery to the alternator (what the Magnum vehicles use), can I relocate the 20 gauge shunt wiring to that new cable to keep the ammeter operational?
2. If #1 is possible, would I also need to relocate the Headlamp/Ignition Switch junction to the new cable, on the alternator side of the shunt splicing? (this would basically be replacing the entire 6 & 14GA factory cable with a 4GA cable.
3. Where is the shunt wiring junction physically located, and what does it look like?
4. Where is the headlamp/ignition switch junction physically located, and what does it look like?
I'd really like to keep the ammeter working. I realize it's almost pointless, but I like it. And I don't like the thought of a nonfunctioning gauge (I already have a voltmeter installed in the rear-window defrost switch location).
Has anyone ever done the "Big Three" charging system upgrade to an FMJ, and is there anything else I'm missing here?
Thanks!
I'm getting ready to swap in a roller V8 in place of my bare bones slant six, and will be upgrading the charging system to the 90A Magnum alternator to support electric fans and other power needs. While I've done charging system upgrades on GM products before (which is as simple as replacing the battery cables), I've never dealt with an ammeter or fusible link wiring before like the Mopars have.
I realize our cars have a shunted ammeter. My Factory Service Manual shows a 6GA cable between the positive battery post and the junction with the ignition/headlamp switch power, with a 10, 12, or 14GA wire continuing on from that junction to the alternator (mine should be a 14GA wire, as it has no power accessories or options). Somewhere between the battery and this power junction, are the two 20GA wires that come off and go through the bulkhead to the ammeter (which is the shunt type).
So now my questions:
1. If I run a new 4GA cable from the battery to the alternator (what the Magnum vehicles use), can I relocate the 20 gauge shunt wiring to that new cable to keep the ammeter operational?
2. If #1 is possible, would I also need to relocate the Headlamp/Ignition Switch junction to the new cable, on the alternator side of the shunt splicing? (this would basically be replacing the entire 6 & 14GA factory cable with a 4GA cable.
3. Where is the shunt wiring junction physically located, and what does it look like?
4. Where is the headlamp/ignition switch junction physically located, and what does it look like?
I'd really like to keep the ammeter working. I realize it's almost pointless, but I like it. And I don't like the thought of a nonfunctioning gauge (I already have a voltmeter installed in the rear-window defrost switch location).
Has anyone ever done the "Big Three" charging system upgrade to an FMJ, and is there anything else I'm missing here?
Thanks!