87-93 130amp Alternator Install How-to

Discussion in 'Late Model Restoration' started by Jarrod@latemodel, Aug 5, 2013.

  1. Jarrod@latemodel

    Late Model Restoration Platinum Sponsor Premium Sponsor

    Nov 29, 1999
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    The factory 75 amp alternator used in the 1986-1993 Mustang 5.0L was, to put it mildly, undersized. Add on something as simple as underdrive pullies or an electric cooling fan and you've effectively killed the ability of the alternator to keep the battery charged. Luckily, turn-key solutions like our SVE 130 Amp Alternator Upgrade Kit exist to solve problems just like this. Watch the video for full instructions on how to install this kit on your Fox Mustang!
  2. Noobz347

    Noobz347 Stangnet Facilities Maint Tech... Er... Janitor
    Admin Dude

    Jan 4, 1985
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    Box behind Walmart
    Great video. I'm a little concerned about the basic upgrade kits though. Those skinny little black/orange wires are barely able to keep up with the factory load and 2G alternator.

    A drained battery and 130 amp alt at 2k is probably enough to set them on fire.
  3. jrichker

    jrichker StangNet's favorite TOOL
    SN Certified Technician Founding Member

    Mar 10, 2000
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    Dublin GA

    Missing from your Video:
    The secondary power ground is between the back of the intake manifold and the driver's side firewall. It is often missing or loose. It supplies ground for the alternator, A/C compressor clutch and other electrical accessories such as the gauges. Any car that has a 3G alternator needs a 4 gauge ground wire running from the block to the chassis ground where the battery pigtail ground connects.

    Problems observed with the video:
    This keeps popping up. I am amazed at the number of people that don't understand that wiring MUST be properly sized to match the current that it is supposed to carry. A 4 gauge wire is the minimum size for a 130 amp alternator, and then only is it s a short length of wire, less than 10 feet.


    Under no circumstances connect the two 10 gauge black/orange wires to the 3G alternator. If the fuse blows in the 4 gauge wire, the two 10 gauge wires will be overloaded to the point of catching fire and burning up the wiring harness.

    Here is the reasoning behind using only a single 4 gauge fused power feed to the alternator. If you use the two 10 gauge black/orange wires in addition to the 4 gauge wire, you have two fused power feed paths. The total current capacity of the wiring is the sum of the fused paths. The 4 gauge path is fused for 125 amps, and the two 10 gages wires are fused for 60 amps. That is a total of 185 amps, which exceeds the capacity of the alternator. Overload can occur without the fuses blowing, damaging the alternator.

    Don't believe me? See http://physics.bu.edu/py106/notes/Circuits.html

    The worst case scenario is that the alternator develops an internal short to ground resulting in a catastrophic failure. The initial short circuit surge current is limited by the resistance of the wiring. The current in a parallel circuit divides up according to the resistance of the branches. If the 4 gauge fuse opens up first, the two 10 gauge black/orange wires will be carrying the short circuit surge current. Depending on the time lag of the fuse links, they may open up before a fire starts or they may not.
    #3 jrichker, Jan 22, 2014
    Last edited: Jan 22, 2014
  4. Foxystang87

    Foxystang87 New Member

    Feb 6, 2014
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