I installed new mini starter the other day and everything was working great. The next morning on the way to work I stopped to get gas when I noticed the ammeter guage "wiggiling" right before I turned the engine off. When I started the truck back up the ammeter guage dove over into the discharge side when I turned the lights on. Truck ran good all the way home just no charge going back to battery.

I tested the battery voltage today and got 12.5v, then started the truck and it was immediatly dropping into the 11v range. So I put another voltage regulator on and it did the same thing. Then I changed the alternator and now Im getting 13.7v at idle and climbing but as soon as you turn lights or any accessories on ammeter guage dives and the the volts drop below 12.5v and slowly continue to sink like its pulling straight off the battery. Raise the rpms and the guage shoots right back up into the positive range. Its like the charging system has no resistance at idle. By the way, the battery is only about 6months old. What should I look at next?
Thanks in advance, Sam

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1975 Dodge D100 2wd Reg.cab 225/6, 727auto, 3.55 gears, Cat delete with 2.25" Thrush Exhaust, Dist recurve by DI, 9.1 comp, Factory aluminum 1bbl intake with heatshield, 63 Jet, Delete ballast with Pertronix Flame Thrower 3ohm coil

It sounds like you already fixed it. If you want better idle speed charging you have to use a different type of alternator.

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Joshua

Joshua, I think you're right....partially. I believe I have 2 bad alternators. The first one was a crappy rebuilt Autozone Duralast that was on the truck when I bought it and looks like its been on there awhile.The second one I put on was an old alternator that has been laying around the garage we took off of a 75 Dodge Royal Monaco 2dr that my Dad bought to get the 360CI engine out of to build and put in his 72 Scamp to race at the drag strip.

I think I'm going to go ahead and get a new alternator and see if it holds charge like it should at idle. The Autozone alternator did a good job at idle till it quit, so we shall see. Where is a good source for a new or good quality alternator?? Rockauto just seems to have rebuilt ones. I really hate to roll the dice with another Chinese paper weight .

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1975 Dodge D100 2wd Reg.cab 225/6, 727auto, 3.55 gears, Cat delete with 2.25" Thrush Exhaust, Dist recurve by DI, 9.1 comp, Factory aluminum 1bbl intake with heatshield, 63 Jet, Delete ballast with Pertronix Flame Thrower 3ohm coil

You might try a cheaper attempt pull the brushes from the "bad" one, might just be they are worn way down.

Richard

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Part of Tyrde-Browne Racing

Hit up the search and find the threads on mounting the smaller and newer denso alt as suggested (pretty sure built an FAQ) that is if you're going to buy another one. And rock auto does have new ones and in the nippo denso as well.

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225, Offenhauser, Holley 350, A833OD, 3:55, GM HEI,99 Durango starter
BOOSTED! WH1C, BIG FMIC, 10#
Operation Noble Eagle 03-05
Operation Iraqi Freedom 05-07
Operation Enduring Freedom 12- 13

Thanks for the suggestions guys I have considered both repairing and upgrading but $40 shipped to my door for a reman Remy is hard to walk away from. I'd like to find a new OEM alternator that someone doesn't want an arm and a leg for but I dont see that happening. I really don't think I NEED all the extra amps of the upgrade or I would invest in that route.

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1975 Dodge D100 2wd Reg.cab 225/6, 727auto, 3.55 gears, Cat delete with 2.25" Thrush Exhaust, Dist recurve by DI, 9.1 comp, Factory aluminum 1bbl intake with heatshield, 63 Jet, Delete ballast with Pertronix Flame Thrower 3ohm coil

Do you really want to do a crap shoot on a Rockauto reman? What will you do if it goes bad? The shipping for warrenty will cost more then getting one locally.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

You're right Charlie that's why, I have not pulled the trigger on ordering one over the internet yet. Only problem is they want $55-60 bucks locally AFTER I give em my core PLUS the 9.75% tax I have to pay here in Tn for the same alternator that costs me $39.63 total over the net. That's why I'm leaning that direction.

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1975 Dodge D100 2wd Reg.cab 225/6, 727auto, 3.55 gears, Cat delete with 2.25" Thrush Exhaust, Dist recurve by DI, 9.1 comp, Factory aluminum 1bbl intake with heatshield, 63 Jet, Delete ballast with Pertronix Flame Thrower 3ohm coil

Spend a little more and do it just once. Then sleep better. Even a properly functioning stock unit had a hard time keeping up with demand in night time, winter, city, driving.

Sam

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I'm with Sam on that! Here are some "built in the U.S.A. Pricey, but should be a one-time thing.
Or the Denso conversion, that needs a bit of custom fitting I think.

BC

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'64 Dart GT convertible, 64 Dart 170 2-door post sedan in faded blue and rust (the Az Dart) & a sixty THREE Dart 170 2-door post sedan in faded blue and rust. (future project)
Early Dart Disorder (EDD) is real, and I've got it!

Old Car Parts Northwest has lots of NOS MOPAR built alternators. Give them a call.

1120 SW 16th St Ste 7
Renton, Wa. 98031

Phone :206-300-1083

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Casually looking for a Clifford hyperpak intake for cheap.

Well after giving it alot of thought, I've decided to go with the late model Denso conversion on this alternator replacement issue. I'm currently shopping around for one, so should I stick with a 90amp or go ahead with 120amp? It seems like you can get either one for the same money.
I don't plan on having a big stereo in the future but would like to go with the electric fans at some point. I guess there is no difference in the wiring method between the two so it shouldnrt matter on the amp size right?

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1975 Dodge D100 2wd Reg.cab 225/6, 727auto, 3.55 gears, Cat delete with 2.25" Thrush Exhaust, Dist recurve by DI, 9.1 comp, Factory aluminum 1bbl intake with heatshield, 63 Jet, Delete ballast with Pertronix Flame Thrower 3ohm coil

I also have a question on the (4) 50amp fuses that go between the alternator and battery. Are these inline fuses or circuit breakers? I'm not very sure of the difference?

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1975 Dodge D100 2wd Reg.cab 225/6, 727auto, 3.55 gears, Cat delete with 2.25" Thrush Exhaust, Dist recurve by DI, 9.1 comp, Factory aluminum 1bbl intake with heatshield, 63 Jet, Delete ballast with Pertronix Flame Thrower 3ohm coil

I went with the high amp Denso and love it! I couldn't find a new one, but found one locally rebuilt. Also upgrade my grounds.

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These ones go to eleven...

Slanted trucker:
[quote]I also have a question on the (4) 50amp fuses that go between the alternator and battery. Are these inline fuses or circuit breakers? I'm not very sure of the difference?[/quote]

A fuse is a current interrupting device that works by melting a small filament opening circuit needing replacement to restore current flow. Fuses can be “fastâ€￾ interrupting circuit at rated amperage, or “slow blowâ€￾ that can take a short burst of amperage above its nominal ratting. Slow blow fuses are used for devices such as a motor starting under load that demands monetary high draw over fuse rating, and settles back to rated amperage once moving.

Automotive circuit breakers use an internal device that when heated by over current condition breaks or opens the circuit, and once cooled will reset allowing current to continue flowing until it over heats again; this is not the case in your home’s electrical service panel that require manual resetting after tripping. Automotive applications of these devices are often used on wiper motor, headlight, and convertible top motor circuits.

You didn’t ask, but fusible links are part of current interruption discussion:
Fusible Links act much like a slow blow fuse allowing temporary over current condition before self-destructing. Fusible links are generally sized four gage smaller than conductor being protected. In other words a #10 gage conductor would be protected using a #14 fusible link. Fusible link utilize special insulation that won’t combust but only melts, and a different grade of copper conductor wire that is more flexible than common automotive wire, are of a specific length that allows for heat dissipation based on circuit ampacity. One can’t just cut in a splice of smaller common automotive wire and expect it to perform correctly interrupting current and suppressing fire hazard from burning insulation.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC