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Thread: 3G Alternator Swap - What am I doing wrong?

  1. #1
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    Default 3G Alternator Swap - What am I doing wrong?

    Upgrading from a 1g 60amp externally regulated alternator to a 3g internally regulated 130amp alternator. The wiring diagram that I'm following is attached. Im getting an immense amount of spark/arcing when I try and connect the battery. The spark/arcing does NOT happen when the 6 gauge (in my case 4 gauge) wire from the alternator to the solenoid is removed altogether. Click image for larger version. 

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    1985 2-Door
    K-Code
    CFI
    K&N Filter
    Race Crank Pulley
    Hooker Max Flow Muffler
    Flex-A-Lite Electric Fan
    3G Alternator
    SVE Wheels
    ET Streets

  2. #2
    I'm an air-conditioned gypsy gadget73's Avatar
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    sounds like the alternator is internally shorted if there isn't some obvious problem with the cable touching the alt case or the red plastic insulator around the output stud being broken. See if your local auto parts store will test it.

    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

    1984 Lincoln Continental TurboDiesel - rolls coal

    Quote Originally Posted by phayzer5 View Post
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

  3. #3
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    Yes, I believe I have both of the problems you mentioned: cable touching the alt case & red plastic insulator broken. It also looks like there was an arc in two places on the alternator case. I've attached pictures for visual reference.
    Click image for larger version. 

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    Click image for larger version. 

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    The pictures are upside down.
    1985 2-Door
    K-Code
    CFI
    K&N Filter
    Race Crank Pulley
    Hooker Max Flow Muffler
    Flex-A-Lite Electric Fan
    3G Alternator
    SVE Wheels
    ET Streets

  4. #4
    I'm an air-conditioned gypsy gadget73's Avatar
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    Looks like the cable touched the screw on the alternator case. Insulator looks OK to me tho. I was thinking if the lower part was gone the terminal could be flopping around. The raised area around it is to make sure the cable comes in at the right angle so it won't touch anything. The eye should lay in the low area, and the raised part of the insulator will keep it from being able to rotate and short. Prob need a different eye if you're using one on a standard battery cable. Those are just too big.

    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

    1984 Lincoln Continental TurboDiesel - rolls coal

    Quote Originally Posted by phayzer5 View Post
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

  5. #5
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    Quote Originally Posted by gadget73 View Post
    Looks like the cable touched the screw on the alternator case. Insulator looks OK to me tho. I was thinking if the lower part was gone the terminal could be flopping around. The raised area around it is to make sure the cable comes in at the right angle so it won't touch anything. The eye should lay in the low area, and the raised part of the insulator will keep it from being able to rotate and short. Prob need a different eye if you're using one on a standard battery cable. Those are just too big.
    Thank you for the words of wisdom, and thank you for helping me fix my problem. I went ahead and insulated the exposed metal on the eye and positioned it in a way that it wouldn't come into contact with the case anymore.
    Click image for larger version. 

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    I will obtain a cable with the appropriate connection at the case. One thing to note is that this car is equipped with an electric choke. I had to splice the electric choke in with the stator plug. For now, this is how all the connections look with the upgraded 3G.
    Click image for larger version. 

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    Heres an engine bay picture showing the stock alternator bracket is still useable. The 3G alternator I sourced was a remanufactured unit out of a 94-95 Mustang. As for the serpentine belt, I ended up needing a 47in. because of my race crank pulley. Duralast PN 470K6 is what I used.
    Click image for larger version. 

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    Again, thanks for helping solve this issue. It is very much appreciated, and I will most definitely pass on the knowledge .
    1985 2-Door
    K-Code
    CFI
    K&N Filter
    Race Crank Pulley
    Hooker Max Flow Muffler
    Flex-A-Lite Electric Fan
    3G Alternator
    SVE Wheels
    ET Streets

  6. #6
    351W & F.A.S.T equipped
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    Another Tudor owner making it happen! I think the 3g swap is one of the best mods you can do on any ‘80’s Ford. It’s the first thing I do on all mine.
    '85 CV coupe- 351W, T5-Z, FAST Ez-Efi, shorty headers, 2.5" duals with knock off flowmasters, 2.5" Impala tails, seriously worked GT-40 irons, Comp 265DEH cam, 1.7rr's, Mallory HyFire 6A, Taylor ThunderVolt 50 10.4mm wires, 75mm t/b, 3G alt swap, 140mph PI speedo, PI rear sway bar, '00 PI booster/MC, 95-97 front spindles, '99 front hub bearings/brakes, '92-'94 front upper control arms/ball-joints, 3.73's with rebuilt traction-lok, '09 PI rear disc swap, '96 Mustang GT wheels with 235/55R17's.

  7. #7
    I'm an air-conditioned gypsy gadget73's Avatar
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    I changed mine after the original barfed and melted the harness on the way to a breakfast meet. Much better alternator.

    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

    1984 Lincoln Continental TurboDiesel - rolls coal

    Quote Originally Posted by phayzer5 View Post
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

  8. #8
    351W & F.A.S.T equipped
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    Quote Originally Posted by gadget73 View Post
    I changed mine after the original barfed and melted the harness on the way to a breakfast meet. Much better alternator.
    Years ago, I had the 65A unit on one of my old fox t-birds catch on fire by the time I got to work. Glad I had the 3g on deck waiting for installation!
    '85 CV coupe- 351W, T5-Z, FAST Ez-Efi, shorty headers, 2.5" duals with knock off flowmasters, 2.5" Impala tails, seriously worked GT-40 irons, Comp 265DEH cam, 1.7rr's, Mallory HyFire 6A, Taylor ThunderVolt 50 10.4mm wires, 75mm t/b, 3G alt swap, 140mph PI speedo, PI rear sway bar, '00 PI booster/MC, 95-97 front spindles, '99 front hub bearings/brakes, '92-'94 front upper control arms/ball-joints, 3.73's with rebuilt traction-lok, '09 PI rear disc swap, '96 Mustang GT wheels with 235/55R17's.

  9. #9
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    I changed mine only after procrastinating after getting all of the parts. Then the 2G died and had no choice. Such an easy swap; so much so that I did it to my Ranger a month afterwards.

  10. #10
    all the CFI are belong to me
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    It's worth noting that the benefits of the 3G over the 1G are maybe less-so than the benefits of the 3G over the 2G, depending on your perspective.

    The biggest motivator most people cite when you mention a 2G-3G swap is the fire hazard that is the 2G charge cable connection, and that's absolutely a priority. The 1G does not have that issue.

    It's still a huge upgrade in electrical output and more importantly, low-RPM voltage stability, with both the 1G and 2G are not great at. It's an inexpensive, easy and super worthwhile thing to do but the fire hazard thing just doesn't exist with the 1G.

    My friend has an 87 Town Car and I've been trying to convince him to 3G swap it for literally years now. It wasn't until I explained the exact mechanics of why the 2G charge connection is a problem, that he understood why it matters. The harness can look completely flawless externally and still be on the edge of burning up.

    83 GM 2dr POTM 10/2019 | 84 TC POTM 1/2017 & 4/2019 | 85 CS | 85 Ranger | 91 GM POTM 12/2017 | Junkyards

  11. #11
    I'm an air-conditioned gypsy gadget73's Avatar
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    Both of my 1g cars are as-built. 100 amp units, which is a little better but still not amazing idle output. Mostly a case of "it ain't broke". I have a nice reman spare that I got for under 20 bucks too, so when one dies it will probably get a like for like replacement. If I didn't have that on the shelf I'd be way more inclined to convert it.

    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC SE, triple black (Timewarp) - poly front bushings, KYB struts and shocks, Holley SystemMax1 lower intake, SilverFox AOD valve body,

    1984 Lincoln Continental TurboDiesel - rolls coal

    Quote Originally Posted by phayzer5 View Post
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

  12. #12
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    There really wasn't a "problem" with the 65amp alternator. I'm prepping this car for more go fast parts, so it needed a 3G to charge the system optimally. It was already starting to get lazy with the charging, considering I added a 3000cfm electric fan that draws 18.5 amps. I have previously done a 2G to 3G alternator swap, but this was my first 1G to 3G alternator swap. It was a cool learning experience and I couldn't have done it without the help of gadget73. Thanks again gadget73, you're an electrical wizard.
    1985 2-Door
    K-Code
    CFI
    K&N Filter
    Race Crank Pulley
    Hooker Max Flow Muffler
    Flex-A-Lite Electric Fan
    3G Alternator
    SVE Wheels
    ET Streets

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