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post #1 of 6 Old 06-07-2011, 07:59 AM Thread Starter
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charging problems

Ok some info I have an aluminum front motor plate that is powdercoated and the alternator is mounted down low using the motor plate . The battery and alternator check out good so I was thinking that I may need a good ground for the alternator seeing it is not grounded to the block anymore .

In the pic you see the alternator if I but a 10 gauge ground wire to the small alternators case bolt and mount the other end to the solid motor mount block bolt would that give me a good ground for the alternator or should I hook up somewhere else . Not sure so I am looking for advice .



85 Capri 310 , 10.1cr , solid roller cam 608"/614"x 242*/248* AFR 205 heads , 1 3/4" headers , super victor intake , holley 750DP , MSd ignition system and NOS 150 shot .
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post #2 of 6 Old 06-07-2011, 01:34 PM
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You should use as large a ground cable to the alternator as you have a power cable from the alternator. The alternator grounds through the case like you mentioned.

The alternator case bolts probably aren't large enough. I would use one of the mounting bolts to attach the ground cable.


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post #3 of 6 Old 06-11-2011, 05:46 PM Thread Starter
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Ok I installed a good quality ground cable and the alternator case is grounded ( verified with a meter ) and the battery still only shows 12.46 volts at idle (130amp alternator ) only things on where the MSD and the fuel pump . As said in the first post the alternator checks good and so does the battery . When the parts store tested the alternator it showed 14.3 volts and it pegged the amp meter at 120 . Any ideas of what to check next.

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post #4 of 6 Old 06-11-2011, 06:05 PM
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Quote:
Originally Posted by 460capri View Post
Ok I installed a good quality ground cable and the alternator case is grounded ( verified with a meter ) and the battery still only shows 12.46 volts at idle (130amp alternator ) only things on where the MSD and the fuel pump . As said in the first post the alternator checks good and so does the battery . When the parts store tested the alternator it showed 14.3 volts and it pegged the amp meter at 120 . Any ideas of what to check next.
Couple things.

Are you checking voltage with the engine cold?

Disconnect the negative battery cable from the battery, and then test the resistance from the alternator terminal to the positive battery cable.

What are the diameters of your crank and alternator pulleys?

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post #5 of 6 Old 06-11-2011, 06:21 PM Thread Starter
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Couple things.

Are you checking voltage with the engine cold?

Disconnect the negative battery cable from the battery, and then test the resistance from the alternator terminal to the positive battery cable.

What are the diameters of your crank and alternator pulleys?
Engine temp has nothing to do with charging if it was it would not test good at the parts store .

Charging system was working great before I installed the motor plate and its the only thing that has changed ( alt pulley is stock and the crank is undersized but not a race pulley .

Ok I will test the resistance from alt cable to battery need a few gator clips LOL battery is in the hatch . Just remember charging system was working great and the battery has been in the hatch for years .

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post #6 of 6 Old 06-11-2011, 06:23 PM
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Engine temp has nothing to do with charging if it was it would not test good at the parts store .
Heat in the cables causes resistance. I've seen more than one foxbody with a 3g put out 14+ volts cold and only 12.5 when it got hot. That's why I ask.

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Originally Posted by 460capri View Post
Charging system was working great before I installed the motor plate and its the only thing that has changed ( alt pulley is stock and the crank is undersized but not a race pulley .

Ok I will test the resistance from alt cable to battery need a few gator clips LOL battery is in the hatch . Just remember charging system was working great and the battery has been in the hatch for years .
Okay sounds good.

'94 GT, White, Cobra hood & bumper cover, '95R wheels
393w, Vic Jr 60cc, XE282HR, Victor 5.8 EFI, 80# injectors, Hooker LT 1 3/4 to 3", Borla proXS
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