upgrade alternator question?

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roylerumble

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I'm installing a v8 in my valiant, putting in a new FBO ignition system (www.4secondsflat.com) along with a new wiring harness.

I figured I might as well upgrade the alternator too. I've read a bit about swapping the mechanical one out for a dual field along with the new electronic voltage regulator.

Apparently they are available in in many mopars in the junk yard. Does anyone know what I can source one out of? What's involved. I'm "automotive electronically challenged", so any help would be great.....
 
Start by reading this:

http://www.madelectrical.com/electricaltech/amp-gauges.shtml

Depending on your dash, you can put a voltmeter in the cluster in place of the ammeter (Read all three pages)

http://www.forabodiesonly.com/mopar/showthread.php?t=119480&highlight=ammeter+conversion

Simplified wiring. The new regulator essentially needs one more wire

http://www.mymopar.com/downloads/Dual_Field_Alternator_Wiring.jpg

And make sure you get a "square back" instead of a "round back." ISOLATED field (incorrectly called dual field) alternators came out in '70, went to the better square back design in ??73, not sure. But don't go by year, as one might be swapped into an older car

Older, less desirable round back on left. Newer, better "squareback" on right

squareroundcomp.jpg
 
The GM one wire is a nice upgrade.
 
I did this on the cheap about 12 years ago,very reliably.I modified the spacers to fit a 1992 buick century 105a unit.I needed the amps for fuel injection/ignition and pumps.I installed a v-drive pulley from a gm dress up kit and used the stock brackets.To wire was simple...connect the "ignition wire to the regulator (after removal) to the "field" wire to the alternator.This will send the required "trigger" voltage to the alternator.Install a replacement gm sealed connector (standard/help/dorman).bypass the ammeter by running a #8 gauge wire from the starter relay supply post to the battery (path of least resistance)On my 505" I used the stock belt.Ran it for over 10 years with no failure.The parts are readily accessible and less expensive than modifying the mopar units and wiring.I know its not mopar but it works
 

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Since your only upgrade is electronic ignition, no need to upgrade your alternator. I have run a round-back on my 65 Newport since 1996 with electronic ignition, Holley TBI, and electric fuel pump. The only time the battery ran down was when a diode failed in the alternator years ago, reducing the output. If I add an electric fan, then I will likely need a bigger alternator. If you go big without addressing your factory wiring and connectors, you may melt them. They usually melt as is.

I would change to an electronic Vreg, regardless. You can get one that matches your harness. I bought 2 for $11 ea on rockauto in last few years.
 
will a 70 dual field/isolated alternator from a 70 and up mopar bolt right in or do I need to change mounts?

I've ordered a harness from Bill Evans at Evanswiring with all the changes made to plug right in. So everything should be plug and play and work with the new electronic ignition, just need to get the electronic vreg.

I want to upgrade to run electric fans, a decent stereo, and electric fuel pump. Is the square back a 60 or 90A alt?
 
Should install easy. I have a square-back in my 65 Dart 273, though it has a later chrome alternator bracket. You didn't tell us what car you have. The square-back is usually rated ~70 A. Its biggest advantage is that it puts out much more current at idle. Electric fans are the biggest current draw, depending on how often they run.
 
roylerumble said:
will a 70 dual field/isolated alternator from a 70 and up mopar bolt right in or do I need to change mounts?

I've ordered a harness from Bill Evans at Evanswiring with all the changes made to plug right in. So everything should be plug and play and work with the new electronic ignition, just need to get the electronic vreg.

I want to upgrade to run electric fans, a decent stereo, and electric fuel pump. Is the square back a 60 or 90A alt?
Click to expand...

Squarebacks did not come out in 70. What came out in 70 were "isolated field" but they were not squareback. Those came later, not too sure when. The thing that makes the squarebacks better is a different design of the rotor / stator, which allows them to produce more output at lower RPM In fact, some of the LOWER rated output alternators put out BETTER amperage at "mid range" RPM than the higher rated units.

And just because it's squareback does not mean high output. I don't know what the smallest squareback was but I'd guess 40-45 A

All Mopar alternators except the "big frame" 105--120A units fit the same bracket without modification.
 
I really like the mopar alternators with the exception of the low rpm voltage drop, or amperage. What ever.
I have run 2 regular 80s gm alternators on 2 separate mopars which eliminated the voltage drop at idle. I also added a fat wire from the alt + to the Batt +. Simple mod back when I was a kid. I totally dont like the look of a gm alternator but they seem to work perfectly and are practically free out of a mid 80s car at a junk yard.

I think you can hook up one of the wires out of a GM alternator to the factory Alt light on a mopar to make that work properly. Pls correct me if I am wrong..
 
Sorry, should have read more. It looks like you have a new wire harness which will allow for 70s voltage regulator and alternator??
 
I have a harness coming that I can run a dual field alternator on. I grabbed two 78 amp ones from some old m body new yorkes that were in the wrecking yard. I'll hit the local parts store for the voltage regulator.
 
Not trynna make fun. I wish you guys would call these ISOLATED FIELD. That is the proper term. It means "not grounded" as the 69 / earlier ones were.
 
This sounds like a cool thread. Keep us posted! Maybe some b4 and after pics?

Are you having the FBO guys setup you up a distributor with proper curve? What parts are you getting from FBO? A whole kit? Which one?
Thanks.
 
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