70 + voltage regulator issue

Previous owner changed the ignition and voltage regulator in my 67 Barracuda. It has a HEI GM type coil on the fender and the 70 up voltage regulator.
My issue: I had to replace the voltage regulator, got one from local autoparts store. After installing I ran the car, I belive the new VR was bad as it blew out both my headlights leaving me with high beams only. Now all the lights puls or strobe with engine RPM making it real interesting driving at night.
Are there better VRs out there or just got to deal with the China junk?
I am running crack backs headlight harness, but i doubt that is part of my problem.

relayed headlights doesnt matter (although they take operating power right off the battery IIRC) Does the VR have a triangle 2 prong plug? What alternator are you running? There is a correlation between the EVR and the mechanical type to the alternator. The islolated field squareback usually uses the EVR. The single field used the points type. The EVR regulated the exciter voltage ground connection so if there was a short to ground on the harness, the alt would go full tilt and produce >19V. the points type regulated the exciter voltage (+) to the alternator, turning it off and on to keep a steady ~13.9V output.

It is the triangle 2 prong plug, Alt is square back. old VR is not in the car and the balast resistor is bypassed.

pulsing could be bad diodes. have alt checked. quick and easy

It didnt puls before i changed the VR, could a bad VR have done something to harm the alt.?

Time to do some troubleshooting analysis.

lets start with what's known.

frederick_76 said:

I had to replace the voltage regulator,

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Why?

frederick_76 said:

After installing I ran the car, I belive the new VR was bad as it blew out both my headlights leaving me with high beams only.

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Why do you suspect the VR blew out the low beams, but not the high beams?
What do you mean by blow out? Did the low beam fuse/breaker open? Is the bulb filiment broken? Neither of those?

frederick_76 said:

Now all the lights puls or strobe with engine RPM making it real interesting driving at night.

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Could be the alternator's return brush is grounding (the one attached to the green wire) but lets not go there yet.

What does the ammeter show?
Have you measured voltage at any time while the engine is running?
If so, where did you measure it?

1...Make ABSOLUTELY certain the VR is grounded
2...Do the "voltage drop test." Voltage drop either in the hot or ground side causes over-charging
3....In the end run, it certainly COULD be china crap quality
4....Check out the alternator both for diode problems and for a grounded field terminal. The two field terminals should show a low resistance between them, and open / infinity to the case


How to check for drop:

1...Turn key to "run" with engine stopped. Access a point as close as you can "electrically" to the VR power / IGN terminal. This can be the blue field wire, which is switched ignition, or the key side of the ballast.

Connect one lead of your meter directly to the POS post of the battery, and the other to the IGN "run" as I just said. You are hoping for a very low voltage, lower the batter. Over .3V (3/10 of one volt) investigate why. Bulkhead connector terminals, ignition switch terminals, or in the switch itself, or ammeter circuit

2...Ground circuit. Get engine running on high idle, and run this test with all accessories off and again with lights, heater blower, etc engaged. Stab one probe into top of battery NEG post, and stab other into mounting flange of VR. Be sure to stab through chrome, paint, rust. As before you are hoping for a very low reading, zero is perfect

Replaced the VR because of not charging the battery.
The low beam filiments broke (lights were only a month or so old).
Why do I suspect the VR caused the lights to blow: ON starting up after the new VR was installed the lights got really really bright then both went out.

Ill run up to the parts store and have the alt checked out today.

frederick_76 said:

Replaced the VR because of not charging the battery.

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OK.
So we can figure out some of it.
I'm going to assume that when you installed the headlight relay harness, there were no other changes.
So I'm guessing you observed the 'alternator gage' showing the battery was discharging.

frederick_76 said:

The low beam filiments broke (lights were only a month or so old).

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I'm not sure what the fuse or breaker rating is that Rob included in the harness. But its certainly possible with a 20 amp or even a 15 amp fuse the low beams could burn out first.
It's definately possibile they were being supplied at too high a voltage.
This could because the alternator is producing at a higher voltage than the regulator is seeing.
In other words there is are voltage drops between the alternator output and the regulator sensing terminal.

frederick_76 said:

Why do I suspect the VR caused the lights to blow: ON starting up after the new VR was installed the lights got really really bright then both went out.

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Its possible, but in this case its just as likely that there is excessive resistance in the circuit.
The reason I say this is because the battery wasn't getting charged.
When the new regulator was installed, the battery was low on charge.
Here's what I think is happening:
The battery is low on charge. When it is offered power at 14ish Volts, its sucking over 25 amps. You can estimate the amount of current its drawing from the ammeter. The ammeter is scaled 40 amps charge to 40 amps discharge.

The differenec between say 30 amps and 5 amps is this -
Voltage is reduced when current flows through resistance. The more current flowing, the more the voltage drops. The regulator only sees the voltage after the resistance. All it knows is the voltage is low and increases the voltage of the alternator's output.

So thats one possible scenario.
Regardless put the battery on a slow charger.
My suggestion is to buy a cheap multimeter. It just needs to be good enough for you to measure voltage near the regulator and compare it to voltage out of the alternator and at the battery.
You wrote the voltage seems to follow rpm. If thats what you meant by pulsing, that narrows it down to not regulating or not getting the correct information to regulate. The multimeter will let you figure out which it is, and if its not getting correct information, you can further backprobe to narrow down where the major resistance is located.

I'd first suspect the splices in the ignition wire (made for the modifcations), and also the alternator output wire where it connects at the firewall.

This is the factory wiring scheme.
You can change it to reflect the modifications made to your car.
If there is resistance at 'P', during high charging situations, the voltage at the battery and at the 'run' circuit (J2) will be lower than voltage the alternator is producing (stud terminal marked BATT).

When current flow is low, then the voltage loss due to resistance will be less.
V = I x R.
I = current. Low batteries demand lots of current.
When current increases, the voltage drop through the resistance increases.

Charging Battery with Alternator - Warning

The alt tested good (including the diodes). The voltage regulator failed when I turned on the accessories, so ill try another cheap china VR, well find out this afternoon.

Well, it wasnt the voltage regulator....I'll try some more tomorrow.

I don't think crackedback headlight relays are fused. They only bypass the harness for power unless I'm mistaken. An over voltage situation would not necessarily blow a fuse, only an over amp draw. Typically a headlight will draw watts (55)/voltage(12) or about 4.5A.