Mechanical voltage regs and electronic ignition systems

Electrical & Ignition

  1. Ross Wooldridge

    Ross Wooldridge Senior Member FCBO Gold Member

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    Hi all,

    I intend to use the adjustable VR that Chrysler used in police and heavy duty applications back in the 60s - I have two NOS ones. The adjustability comes in the form of idle speed alternator output - you can bump it up a little to reduce or eliminate the traditional brownout our cars demonstrate when at idle in gear with lights/AC/radio on etc. This particular VR is what my Monaco came with due to the police engine package that it received - the factory used a special mounting bracket on the inner fender for cooling, as opposed to mounting it on the firewall as they typically did.

    [​IMG]

    You can see the VR on my inner fender on it's bracket, just in front of the booster.

    [​IMG]

    My concern is this: I will be using either Pertronix OR the Mopar Performance electronic ignition system (with a generic box rather than the failure-prone orange box) and it's my understanding that electronic ignition systems don't like mechanical VRs and vice versa. In the past I've used one of the electronic VRs in a vintage case (from Bill Corcoran) with no problems, but they still brown out at idle just like the mechanical standard ones.

    What can/should I do to be able to use both my electronic ignition and the vintage adjustable mechanical VR? They are kind of expensive, and I don't want to burn them up... lol. I wouldn't be opposed to peeling the case off one to have a look as long as I felt I'd be able to not mark it up...

    For what it's worth, I am using a single wire original style round-back alternator.

    I've already had a response from @Mike66Chryslers in a PM, and this is what his thoughts are:

    Interesting question. I presume that the main problem is the opening and closing of the contacts in the Vreg puts high-frequency noise on the power rail. If the ignition ECU doesn't have sufficient noise filtering, this noise will go right into the ECU electronics. The ECU power is usually wired to the same ignition-switched circuit as the Vreg, so there wouldn't be much else like a long wire run to dampen the noise.

    Ideally I would like to put an oscilloscope on the IGN terminal of the Vreg to see what noise the Vreg is injecting onto it, then design a filter to block those frequencies at the source. You may be OK just putting a condenser from a distributor between IGN and ground, and one of those snap-on ferrite chokes with the IGN wire wrapped around it a couple times, to make an LC filter.

    The noise could also be getting onto the power rail from the FLD output and through the alternator. Certainly the switching noise is getting onto the Vreg FLD output, but I think it's a lot less likely that it gets through to the alternator BAT terminal though.


    I am interested in what people have to say and their experience of similar situations.

    Thanks all!
     
  2. Davea Lux

    Davea Lux Senior Member FCBO Gold Member

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    There are a couple of problems with using the mechanical regulator with electronic ignition. First, the electronics need a constant, steady flow of voltage to function properly. You do not get this with a mechanical regulator because the voltage is constantly being interrupted/adjusted by the points opening and closing. The second issue is that the mechanical points opening and closing produce an electrical arc which introduces static to the circuit. Static causes voltage spikes which can short out electronic components.
    An electronic voltage regulator still has switch gear to control the voltage, but the difference is that the electronic switches open or close in a matter of nano seconds, ie. very rapidly, which for all intents and purposes creates a constant voltage with no arcing. The mechanical regulators cycle much slower because of the relatively heavy mechanical switch gear.

    Yes, you could probably design a filtering/buffering system to protect the electronic ignition system if you are particularily adept at electronics, but it would be a lot more work than simply converting to an electronic regulator which already performs that function. Another thing to consider, is that the windings in the single pass type early alternators were not designed for operation with electronic ignition. They also produce lots of static (noise). This was the main reason Chrysler went to the later dual pass, static suppressed alternators when they converted their cars to electronic regulators (1970) and a couple of years later (1973) to electronic ignition. They got the electronic engineering homework done correctly and the systems were highly reliable.
    The orange box ECM units were reliable when properly installed, and that is the key. There must be clean grounds, tight connections, and the proper charging system components, otherwise the the ECM will burn out, as will the Pertronix system. A lot of folks installed their shiny new ECM with wire nuts or crimped connectors on the old style charging systems and they worked fine, until they didn't and found themselves on the side of a freeway some place with the hood up.

    The ECM reproduction orange box units available these days are mostly made in China and have serious quality control issues, so if you go that route, try to find a NOS unit that was made by Chrysler. This is pretty much true of most ECM's currently available.
    Pertronix has had a lot of these issues also.

    Dave
     
  3. Ross Wooldridge

    Ross Wooldridge Senior Member FCBO Gold Member

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    Could I wire the ECM to a battery feed and bypass the VR/Alternator to achieve the required constant voltage source?
     
  4. Mike66Chryslers

    Mike66Chryslers Active Member

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    Dave, we are mostly in agreement on the electronic versus electromechanical regulators, but there is no difference in the alternator design, except that one brush holder is grounded to the case in the earlier system. The later alternators are not "dual pass". They are also not "dual field", which is a widely misused term. Technically they are "isolated field", which results in "dual field terminals".

    In the early charging system, one field terminal is grounded and the Vreg varies the positive side current to control the field strength in the alternator. At idle, the alternator isn't spinning fast enough to supply enough current to maintain its own field and prevent the system voltage from drooping, even with the Vreg commanding full output. So at idle the alternator output is low and your headlights dim, etc.

    In the later charging system, one field terminal is wired to full battery voltage and the Vreg regulates the negative-side current instead. Not only is it easier to design an electronic transistor circuit to implement this design, it also regulates better at low RPM than the older system.
     
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  5. traintech55

    traintech55 Senior Member FCBO Gold Member

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    I.M.H.O. I would change to the 1972 or newer alternator, the electronic regulator, then the electronic ignition. Like stated in an earlier thread, Chrysler did ALL the engineering on this and made a totally reliable system.
     
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  6. Ross Wooldridge

    Ross Wooldridge Senior Member FCBO Gold Member

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    I hear you - I certainly went that route with brakes (70 Fury discs, but used the 65-68 disc booster - hard to see the discs, easy to see the booster which is year correct). I'm doing a bit of the enigma restoration: trying to keep things as factory original as possible while doing reliability upgrades... I'd prefer to keep my original charging system if at all possible... call me silly. I may go back to points if required, but I do like the consistency of my electronic ignition, if I can hide it! Maybe I'll see about putting a modern electronic regulator inside the adjustable case... but then that puts me back to the dimming at idle issue.

    Can't I just provide a solid power source to the ECU as per my previous response to DaveaLux?
     
  7. 70bigblockdodge

    70bigblockdodge Old Man with a Hat FCBO Gold Member

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    Are you really piling all that many miles on the car that points are wearing out fast enough to warrant stressing over electronic ignition.
    The brakes I can understand, they can be a safety issue in modern traffic.
    Your points should not be causing a safety issue, i.e. breakdowns or high speed miss. The electronic will only provide long term durability/less maintenance which is why Chrysler switched, to compete with GM and Ford on extended maintenance. You will gain no performance.
    I think it would work fine, I have seen them working with a eletromechnical regulators.
     
    Last edited: Jan 10, 2019 at 4:12 PM
  8. Ross Wooldridge

    Ross Wooldridge Senior Member FCBO Gold Member

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    I do drive them quite often - so I'm not so much worried about not gaining performance as I am in ensuring reliability. That being said, it's not a big deal, I'm just primarily trying to get rid of the idle dimming. I ran points on the car in question for years, with no issues other than the dimming, and plenty of performance! See the video (taken when the car was still equipped with a points ignition system - turn the sound up too!):

     
  9. Davea Lux

    Davea Lux Senior Member FCBO Gold Member

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    The design was mostly similar, but the latter alternators had better insulation on the field windings which was supposed to decrease the amount of generated static. Otherwise I agree with you.

    Dave
     
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  10. Ross Wooldridge

    Ross Wooldridge Senior Member FCBO Gold Member

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    Dave, I think I can deal with the static noise by installing suppression systems as described above. But I need to know if I can power the ECU from the battery, bypassing the VR, using a key-on relay so that the VR isn't constantly powered when the car is parked? I think I can, but I'm not knowledgeable to know for sure if that will solve the issue that you described in your first response.

    Thoughts?
     
  11. Davea Lux

    Davea Lux Senior Member FCBO Gold Member

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    The ECU and VR can certainly be powered thru the relays that you suggest. The problem is that DC current flows in one direction, so no matter how you wire the ECU, the static produced by the mechanical regulator is still going to be flowing thru the electrical system as are the temporary spikes in voltage. The normal wiring for the ECU was powered the key on to complete the circuit, you would be doing the same thing in a more round about way by using a relay.

    Dave
     
  12. Mike66Chryslers

    Mike66Chryslers Active Member

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    I was not aware of that. Thanks.

    Powering the ECU from battery voltage through a relay should help because it won't be on the same circuit as the Vreg, and the battery will help to filter any noise injected onto the power rail. Do not connect the Vreg through a relay though. You want the Vreg sense voltage to be the same as most of the car's electrical systems see, so that it regulates effectively.
     
  13. 70bigblockdodge

    70bigblockdodge Old Man with a Hat FCBO Gold Member

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    The alternator should not be making pulsing. Your diodes are bad if it does. The clicking points vary the voltage to the field in the rotor of the alternator, changing the magnetic field strength, which changes the amount of amps produced. They have nothing to do with the buzz of leveled off one half alternating current that charges the battery, all altenators produce electricity this way even the new ones in 2019 and new cars have quite a bit of electronics in them
     
  14. traintech55

    traintech55 Senior Member FCBO Gold Member

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    If you want to keep the car as original as possible, you would keep the points, and mechanical regulator. Changing to a newer system that Chrysler engineered is a good upgrade, plus if you do the wiring correctly, you can put it back to stock anytime you want.
     
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  15. Ross Wooldridge

    Ross Wooldridge Senior Member FCBO Gold Member

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    It's not pulsing just dim at idle when running lots of accessories, apparently a common complaint when all else is good... hence the adjustable VR.
     
  16. cbarge

    cbarge Senior Member FCBO Gold Member

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    Ross for the headlight dimming do the headlamp relay harness like on your wagon and the BoaB.
    It can be wrapped to look stock and hide the relays to keep a stock look.
     
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  17. Mike66Chryslers

    Mike66Chryslers Active Member

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    As I said in my previous reply, do not power the VR through a relay, only the ECU. The VR needs to sense the voltage that the system loads see in order to regulate effectively. If you connect it directly to the battery through a relay, it would be as ineffective as a GM 1-wire system. Yuck. ;)

    Yes and no. The electrical noise from the VR points opening and closing can be thought of as AC noise riding on top of the DC, coming out of the VR's IGN voltage sense terminal. In theory filtering at that point could contain it, but arcing produces noise at all different frequencies. The battery will dampen these, but if the ECU is wired into the factory wiring, it will be on the same ignition-switched circuit as the VR, which is electrically very close. Hence the idea of putting the ECU on the battery supply with a relay is probably helpful.

    I don't believe that the noise from the VR's points controlling the alternator field strength will get through the alternator into the main battery feed. I could go on at length about why, but let's just say we don't worry about noise being introduced by the alternator brushes arcing against the commutator, and hopefully leave it at that. That is why I am focusing on noise introduced onto the ignition-switched power rail at the VR's IGN terminal.
     
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  18. Davea Lux

    Davea Lux Senior Member FCBO Gold Member

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    Since the main problem seems to be the dead spot, dim lights at idle, the wiring of the lights thru a relay might help. Going to the next larger alternator might also help.

    Dave
     
  19. Big_John

    Big_John Illegitimi non carborundum FCBO Gold Member

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    IMHO, lot's of guys have done the ignition conversions and done it all different ways. Stock mechanical VR, Mopar Perf's "constant output" VR, electronic VR, conversion to isolated field alternator and so forth. They all seem to work... The best seems to be the electronic VR or the isolated field conversion. Reliability seems to be more about doing the wiring right, good grounds and solid connections. Seems simple, but we've all seen twisted and taped wires and crappy grounds with guys having all sorts of issues... But I digress.

    It all adds up to reliability. IMHO, I don't think it will really make a big difference. Worst case, you carry a spare ECU or points distributor (if you go with the Pertronix), which isn't a bad idea no matter what.

    If it were me, I would go the simplest route and go with the electronic VR that Bill sells.

    Regarding the "brown out", that can be helped with headlight relay (as mentioned) that eliminates the voltage drop through the switch and bulkhead connections. I think it's also helped with the "MAD" bypass and that's another very simple thing to do. It all helps, but may not completely eliminate the problem.

    Just to toss this out there... I'd look at doing the HEI conversion with a Mopar electronic distributor, but that's another conversation. That seems to be a very robust ignition system.
     
  20. Ross Wooldridge

    Ross Wooldridge Senior Member FCBO Gold Member

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    The wiring of the headlights with relays as suggested by Cbarge is already done (he sold me the kits for both my cars before I started to restore this one), and things did improve dramatically, as did addressing the bulkhead's connections etc as part of routine maintenance..

    Regarding the MAD conversion - interestingly, because the car was equipped with a police issue wiring setup from the factory, the main power feed going to the amp gauge does not route through the bulkhead but has it's own sturdy junction terminal bolt on the firewall, which then has a separate wire fed through a special hole and grommett to the amp gauge. Much safer, easier to service and clean etc, and common to police cars of the era, along with the adjustable Vreg as mine was equipped with. Because of that I don't feel the need to do the MAD conversion. My wagon is another matter however. I certainly keep tabs on the engine compartment wiring regularly. If you blow up the engine compartment pic from my first post all the police stuff is visible. I think my car should have had a Leece Neville alternator too, but I've not been able to confirm that at this point.

    I've totally renewed the entire wiring harness in the car as part of the restoration - everything is tickety-boo and in as new condition - all connectors dissassembled etc. I'm just trying to eliminate the one known issue these cars had - dimming at idle...
     
    Last edited: Jan 10, 2019 at 10:31 PM