Round Back Alt w/ Elec. Ign?

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mopowers

mopowers

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Should a single field-wire round back alternator be used with electronic ignition? Or is a square-back conversion recommended?

I have no electronic accessories, other than the MP electronic ignition. I've bypassed the ammeter, ran a large charging wire directly from the alternator to the starter solenoid, and have installed headlight relays. I just realized I have a round back alternator and want to make sure my electronic ignition is operating properly. Thanks for the input.
 
The original "deal" with the older (69/ older) is that the VR is a relay / mechanical type VR. Most or all of the modern replacement regulators are not, they are acually electronic, in a similar case. You can easily tell if yours is mechanical or not. Just look at the bottom. The mechanical ones have two large wire wound power resistors there, the electronic replacements do not. Below is the old mechanical style showing the resistors

440-1621-large.jpg
 
67Dart273 said:
The original "deal" with the older (69/ older) is that the VR is a relay / mechanical type VR. Most or all of the modern replacement regulators are not, they are acually electronic, in a similar case. You can easily tell if yours is mechanical or not. Just look at the bottom. The mechanical ones have two large wire wound power resistors there, the electronic replacements do not. Below is the old mechanical style showing the resistors

440-1621-large.jpg
Click to expand...

Mine is electronic. Does that mean, my electronic ignition should live a happy life with my single field round back alternator? Or would it be worthwhile to upgrade to a squareback alternator and corresponding VR?
 
mopowers said:
Mine is electronic. Does that mean, my electronic ignition should live a happy life with my single field round back alternator? Or would it be worthwhile to upgrade to a squareback alternator and corresponding VR?
Click to expand...

Maybe no answer means it doesn't matter. :D

The only real difference is the squareback puts out more amps at lower RPM's than the round back.
Depending on idle RPM's your lights might be a little brighter at stoplights with the squareback.

You already have one of the better regulators, so you should be good to go.
 
There is available from Bosch an electronic voltage regulator that plugs straight into the harness on older cars. The field wire is only for the charge sensing of the system. Some times the wire falls off the back of the alternator. For some reason the system does not go into a discharge even when running and lights on but you will notice your lights get dimmer.
Obviously with time you will get a flat battery. This fall off of field wires was a very common problem with dodge army trucks that were on rough terrain a lot.
 
If you have an electronic regulator you are fine. The type of alternator does not matter. The problem, once again, was the older "relay" type VR
 
I've ran the electroinc conversion for many years on the single field alternators in 67-69 abodies... No problem...
 
mopowers said:
Should a single field-wire round back alternator be used with electronic ignition? Or is a square-back conversion recommended?

I have no electronic accessories, other than the MP electronic ignition. I've bypassed the ammeter, ran a large charging wire directly from the alternator to the starter solenoid, and have installed headlight relays. I just realized I have a round back alternator and want to make sure my electronic ignition is operating properly. Thanks for the input.
Click to expand...

In regards to deleting your ameter that's fine I assume you just joined the wires together. That's fine but when I have done this for myself and others I use splade connections cut off the existing lugs and plug in one of the flat blade type fuse holders with a cap. I insert a 30amp fuse with the extension created by the wire on the fuse holder it is enough just for the fuse to hang right next to the steering column. Just in case you get a major short behind the dash it might save something. Also you can create a security device because some jerk cannot get power to go. ( by removing the fuse)
 
krazykuda said:
I've ran the electroinc conversion for many years on the single field alternators in 67-69 abodies... No problem...
Click to expand...
Ditto. My 65 Newport has had electronic ignition (Crane XR700) since 1991 and TBI (Holley Pro-jection, w/ electric fuel pump) since 1995. Still using the round-back alternator and my battery stays charged. I did convert to an electronic Vreg at some point during this. The headlamps should be "bright enough" even if the alternator can't keep up at idle and voltage drops to the battery's 12.6 V from "normal running" 14.3 V. You don't need them brightest until moving anyway (consider it a "feature"), but I haven't noticed any loss. It isn't like old 2-stroke motorcycles that had no battery and their lights dimmed way down at red lights. Regardless, you are much better than all the newish cars running around with fogged out plastic headlamps. I haven't seen a newer M-B car that didn't look freaky with its totally fogged slanted headlamps.
 
I run square back on one car and original round back (cause I'm cheap) on the other with no problem other than those mentioned.
 
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