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#2413232 - 12/04/17 05:42 PM Alternators
moparphilll Offline
top fuel

Registered: 08/20/03
Posts: 2259
Loc: Fargo ND
What year did they switch to the square backed and Why?


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#2413239 - 12/04/17 05:53 PM Re: Alternators [Re: moparphilll]
Mattax Offline
super stock

Registered: 02/28/10
Posts: 976
Loc: Phila. Pa.

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#2413327 - 12/04/17 08:52 PM Re: Alternators [Re: moparphilll]
NachoRT74 Offline
master

Registered: 08/14/07
Posts: 4862
Loc: Caracas, Venezuela, SouthAmeri...
thats a 70/71 dual field round back

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#2413409 - 12/04/17 11:20 PM Re: Alternators [Re: NachoRT74]
moparphilll Offline
top fuel

Registered: 08/20/03
Posts: 2259
Loc: Fargo ND
what is dual field used for higher amp?

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#2413481 - 12/05/17 07:30 AM Re: Alternators [Re: moparphilll]
NachoRT74 Offline
master

Registered: 08/14/07
Posts: 4862
Loc: Caracas, Venezuela, SouthAmeri...
all alternators are technically dual fields, because to get a full magnetic field requires both poles or fields ( + and - ). They are simply called single or dual fields just because the fields are wired or not.

single fields get the - field by a grounding brush straight to the case and the + from reg which is sourced from ign switch ( so, wired ) to one isolated brush. You'll find on them just one field wire

dual fields get both fields wired... being the + constant from ign key, and - feeded from reg. these require both brushes isolated, hence they get two wires and tipically called "dual field "

69 is the crossover year from the single to dual field setup. Mostly of Mopars were still single field but some high equipped C bodies began to get dual field on late 69. Then 70 become standard dual field setups on all mopars.

72 as mentioned the alts changed from roundback alts to squareback alts.

dual or single fields, round or squarebacks have nothing to do with the output itself, but theway how they worked and easier to be serviced... Dual fields are more efficient just because they got electronic regulators which are more efficient on how they work.

Squarebacks specs and advantages, are exposed on the link mattax posted

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#2413498 - 12/05/17 08:29 AM Re: Alternators [Re: moparphilll]
Mattax Offline
super stock

Registered: 02/28/10
Posts: 976
Loc: Phila. Pa.
Maybe its worth explaining how alternators works, and then other things make more sense.

The Field is a spinning electromagnet. The magnet is made by winding wire around and putting electricity into it. The more electricity into the electromagnet, the stronger the magnetic Field.

So the field circuit is the path to get the electricity through this spinning electromagnetic that creates the magnetic field.
A positive wire connects to a carbon brush that rubs against a copper ring on the rotor. This ring then connects to the windings. The other end of the wire windings are connected to another ring, a brush and then a ground wire.

Power through the field can be regulated by controlling the positive wire, or the ground wire. When controlling the positive, the negative side can be grounded to the metal case. When controlling the negative, the ground wire must be insulated from the case.

Regulators that control the negative (ground) still need a positive wire connection. The positive informs the regulator of system voltage.

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#2413500 - 12/05/17 08:34 AM Re: Alternators [Re: moparphilll]
Mattax Offline
super stock

Registered: 02/28/10
Posts: 976
Loc: Phila. Pa.
There's a part number and date code stamped on the side of the alternator case. As long as the parts haven't been mixed in a rebuild, those are useful.

More powerful alternators have more copper windings, and therefore were more expensive. They also can get hotter. That's the basics anyway.

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