Pre 1970 vs. Post 1970 Alternators / Systems -- SOLVED IT - See Post # 12

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RPMagoo

RPMagoo

Just An Old Motorhead
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I'm still dealing with electrical problems, on My 65 Valiant. --- I plan to switch to a post 1970, flat back, alternator, with a external, solid state, voltage regulator. Since the alternator will have 2 field wires, I've been told that I can simply connect each of the 2 wires to the field posts, on the alternator, (1 wire is already in the wiring harness, from the old set-up) then connect the 2 wires together, at a point prior to the connector at the voltage regulator. The regulator is a VR706 type (Ign. & fld. connectors only). -- My questions are -- (1) Is this true ? -- (2) Will this cause any problems ? -- (3) Will this allow Me to take full advantage ( steadier lights etc.) of the switch to the newer alternator. -- I assume that the new alternator will be 78 or 80 amps vs. 60 amp on the old, pre 70, 1 field unit.
 
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RPMagoo said:
I'm still dealing with electrical problems, on My 65 Valiant. --- I plan to switch to a post 1970, flat back, alternator, with a external, solid state, voltage regulator. Since the alternator will have 2 field wires, I've been told that I can simply connect each of the 2 wires to the field posts, on the alternator, (1 wire is already in the wiring harness, from the old set-up) then connect the 2 wires together, at a point prior to the connector at the voltage regulator. The regulator is a VR706 type (Ign. & fld. connectors only). -- My questions are -- (1) Is this true ? -- (2) Will this cause any problems ? -- (3) Will this allow Me to take full advantage ( steadier lights etc.) of the switch to the newer alternator. -- I assume that the new alternator will be 78 or 80 amps vs. 60 amp on the old, pre 70, 1 field unit.
Click to expand...

Hi,

The stock 65 Valiant alternator was something like a 35 amp unit. What you are calling a "flat back" alternator is called a "square back" and is a 1972 and up type usually rated at 60 amps. Unless a rebuilder turned it into something else which is entirely likely today.

You will need a new connector to fit your new electronic type regulator. You would connect the existing green wire to one field connection on the alternator and the other end of the green wire to the green wire on the new regulator connector. The blue wire on the regulator connector goes to the RUN side of the ignition switch, usually a blue wire on one side of the ballast resistor. You will also need to run a new blue wire from this same point to the second field connection on the alternator.

The square back alternator will produce more output at engine idle that the original alternator but, don't expect it to be like a modern car. The lights are still likely to dim at idle.
 
The problem with the above post is VR706 is the electronic version of the early style regulator, and suggested wiring will not work for that.

To make it work, the last part about connecting the second field wire to blue wire, instead should connect to ground at alternator. Or more simply, leave all wiring for the early system, and connect the second field terminal to ground.

The other option is to use late model regulator and associated wiring with mating connector, per above post.
 
Here's the info that I was referring to -- Any problems with this ?? -------------
Swapping to a 2 Wire Alternator.JPG
2 Wire Alternator - Info.JPG
 
RPMagoo said:
Here's the info that I was referring to -- Any problems with this ?? -------------View attachment 1714974170 View attachment 1714974172
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They are talking about a new post 70 style regulator. The VR706, is an old, or early style regulator .. only used for alternators with single external field wire, or where the other field connection is grounded. Such a regulator powers the field connection. If you use it incorrectly, with the marked in yellow instructions, there will be near zero volts provided to field winding since both field terminals will have the same potential, no current will flow. And no alternator action...no worky. The later alternator field coil is isolated from ground.

New style regulators, sink one field wire to ground, to complete the circuit, where the other field wire is powered by the blue wire that is hot with ignition on.
 
KitCarlson said:
-- They are talking about a new post 70 style regulator. The VR706, is an old, or early style regulator ..
New style regulators, sink one field wire to ground, to complete the circuit, where the other field wire is powered by the blue wire that is hot with ignition on. --
Click to expand...
-- My friend corrected Me , on that today. -- If I get a 2 field alternator, and a "new style (not a VR706) voltage regulator - then is it Ok to hook-up as per the info that I provided? --- If so, that is pretty simple / easy. -- Thanks
 
KitCarlson said:
-- Yes, now you are on the right track. Enjoy success. --
Click to expand...
-- Thanks -- Hopefully, there will be a few more weeks to enjoy it, before the dreaded cold & nasty weather returns. -- Obviously, I still have The Valiant. - I got frustrated, and offered it for sale, too cheap. Thankfully, no one bought it. - In order to kill the For Sale Post, I indicated that it was sold.
 
Surprised you are back on the Alt/Reg again. Thought you had both tested and confirmed as good units already.

I run the same older round back single field and newer solid state (old looking pre-70) regulator. I removed the Mopar Blue unit to get a more authentic look. This combo works great for me! I have been very happy with no issues!

I am not sure what your real problem is but it seems minor enough that a competent mechanic should be able to isolate it for you. I have not read all your posts, but to re-cap.

Flickering lights at idle and jumpy amp gauge
Tightened amp meter feeder wires and fixed.

Now you have the issue at cruise speed?

Do you have electrical loads higher than anticipated from a factory car? Have you done the MAD modification?

Does the issue only happen when the lights are on?

Are the body grounds from engine to firewall and or Negative cable to radiator support connected?

Have the main feed wires in and out of the bulkhead connector been checked and cleaned? As well has the ignition feed to ballast/regulator through the bulkhead been checked and cleaned?
 
1969383S said:
- Surprised you are back on the Alt/Reg again. (1) - Thought you had both tested and confirmed.
I have not read all your posts, but to re-cap.
(2) - Flickering lights at idle and jumpy amp gauge
(3) - Tightened amp meter feeder wires and fixed. (4) - Now you have the issue at cruise speed? (5) - Do you have electrical loads higher than anticipated from a factory car? (6) - Have you done the MAD modification?
(7) - Does the issue only happen when the lights are on?
(8) - Are the grounds from engine to firewall connected ?
(9) - From neg. batty terminal to rad support ?
(10) - Have the main feed wires in and out of the bulkhead connector been checked and cleaned? (11) - As well has the ignition feed to ballast/regulator through the bulkhead been checked and cleaned? --
Click to expand...
--------- (1) - So did I (2) - Yes - (3) - eliminated amp gauge & installed a volt meter. (4) - Yes (5) - None - no radio (6) - No (7) - Happens with or w/o lights on. (8) - Cleaned, paint scraped & connected. (9) - New one 6 gauge (10) - Yes (11) - Yes. --------- Going with 70+ 2 field alternator and new style VR - see post #7 & 8. -- Hopefully that does it. -- If not - I will probably go with new under hood harness + dash harness, if needed, --- Already, had several look at it, run various tests etc., tried another dash panel, installed a new ign. switch, eliminated the dimmer switch, & light switch. -- Thanks for the help from ALL. -- Let's kill this series of posts, and get on to better topics.
 
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Got it !! -- Bought a new 2 wire (2 field connectors) post 1970 alternator, and a new, corresponding, voltage regulator -- hooked the 2 wires (ign & fld), that ran to the old regulator, together, and soldered them to the blue wire/pig tail that feeds the new voltage regulator. -- ran a new wire, from the negative field connector, on the new alternator, to the lower feed wire on the new voltage regulator, -- Same jumpy volt meter, and flickering head lights. -- Oh shi_ !! -- Then I read info, from another person, on the Internet, who had experienced the same problem, on a 68 Mopar -- And Solved It This Way -- Tie in a wire from the blue pig tail, on the new voltage regulator. and run it over, and tie it in, to the ballast resistor. -- I did this -- BINGO PROBLEM SOLVED.. --End of a long story.
 
Not sure I really understand what you did, but it sounds like you bypassed your real issue. All I can say is I am very happy you solved your issue and that you are excited and happy! Good work!
 
1969383S said:
-- Not sure I really understand what you did, but it sounds like you bypassed your real issue. All I can say is I am very happy you solved your issue and that you are excited and happy! Good work! --
Click to expand...
-- Ran it 45 miles - no smoking wires, or hot items yet.
 
Glad you got it fixed Magoo.... :)
Ma Mopar loves to pick up lot of feeds off one wire.. Bad grounds also cause issues... Got to have grounds also.. :)
 
racerhog said:
-- Glad you got it fixed Magoo.... :)
Ma Mopar loves to pick up lot of feeds off one wire.. Bad grounds also cause issues... Got to have grounds also.. :) --
Click to expand...
-- Hi Bob - Haven't heard from You in a while - Glad You're still cook'n. -- Worked over the grounds real good & added one direct from the battery to the radiator support. -- Don't understand what the ballast resistor had to do with it -- But -- the problem has went away. So far, so good. --
 
For newbies reading, this post is too convoluted to follow the technicals. There are many posts that explain it better. Search for those by 67Dart273.
A few highlights:
Ignore post #5 description since totally wrong. There is no "two field" alternator. Both types had a single field (coil w/ 2 ends, routed thru brushes). The difference is that round-backs had one field terminal bolted to the case (gnd), whereas square-backs had two isolated field terminals (2 field wires). Caveat, a few late round-backs have 2 isolated terminals. The early VR used "high-side control", i.e. varied the positive terminal, w/ the other terminal grounded. Later VR used "low-side control", w/ positive terminal at fixed 12 V and varied the other terminal. Reason - easier w/ transistors and same used in my 1996 Voyager but Vreg is inside PCM box.

Can I use a square-back alternator by just grounding one terminal? Of course, isn't rocket science.
Why should I? Square-backs output more current, esp. at idle, plus easier to source today.
Can I get an electronic Vreg for a round-back? Yes, $11 at rockauto when I last bought (some PN's above).
Can I install a later "square-back" Vreg? Yes, but will need to run another wire for 12 V IGN to the alternator.
Must I install the Vreg on the firewall? No. I put a later one on the inner fender beside the alternator in my 65 273 since simple and obvious wiring.
 
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