Voltage Regulator and/or Ballast fails

I have a 1967 Barracuda with a Slant Six. Based on the VIN, I believe the car was originally a V8 small block. I either have an electrical gremlin or something is mismatched in my system as either the Electronic Voltage regulator (2-Pin) or Ballast (2-Pin) will fail occasionally after sitting or when attempting to start. It will work again as long as I continue to replace either one of those parts (depending on which one is broken).

The car has been upgraded with the following:
- Pertronix Ignitor at the distributor (removed points)
- Electronic Voltage regulator (which doesn't appear stock given the year).
- I also assume the alternator has been upgraded to match (how do I know?)

My initial thought is something in the system isn't compatible (alternator or voltage regulator) or something is simply mis-wired completely, but I don't know what to look for given that a portion of the system was upgraded by a predecessor. I'm contemplating ordering a new wiring harness since the old one has seen better days but would rather have a finite answer before attempting to do so, plus I don't know what wiring harness to order since I don't see listings for slant sixes on Classic Industries or Year One's sites.

So the questions I have are as follows:
- What do I check OR is something in my system incompatible?
- Which wiring harness do I go with (original breaker point ignition?)?
- Do I go with a Big Block or Small Block harness (Is one the same as a Slant Six)?

Hi, Big Block cars used the same engine harness as a 6 cyl car. Just a thought, do some research on the Ohm rating of your ballast resistor. If converted to electronic ignition the ohm rating of the ballast could be mismatched when using the original ballast from the points system. Ballasts are available with different ratings. This could cause the ballast to over heat and go faulty prematurely. I cant comment on the alternator wiring or set up without seeing it. Worth a look IMO. Other thoughts are sure to come for other members.

Thanks. To add, the car is turning over, just not firing. The alternator in an Autozone DL75334 65 Amp (fits newer 72 up).

The first thing that I think of that can kill these parts or anything electronic is water. So does this car sit out in the weather?

Nope. Stays in a heated garage.

Pertronix 1 2 or 3 ? Pertronix 1 you use the ballast . 2 & 3 the ballast is by-passed.

How do you figure out which one is broken.
BTW, the car will start and run just fine with the charging system completely disabled. That is to say, you can remove the VR, and/or the alternator, and it will still start and run, so long as the battery is up for it.

The charging system wiring should be fairly independent of the ignition. The only place they overlap is that they share the IGN feed from the key-switch. Since removing Vreg fixes your "no spark" issue, it sounds like the mis-wiring culprit so read below.

If your alternator has a single field terminal (male spade connector, termed "57 terminal"), then 1 wire should run from it to the "FLD" terminal on your Vreg. The case of the Vreg should be grounded to the body (and thus BATT-). The incoming IGN terminal is labeled "IGN", as I recall. There are electronic versions of this early Vreg.

But, if your Vreg has a triangular plug w/ 2 terminals, it is the later style (~1971+) and won't work with an early alternator. If they connected the "FLD" wire to an early alternator, that would short to ground to draw down the IGN source. That would disable your spark system, probably killing Vreg as well (solid-state usually dies shorted). When working correctly, the charging system should produce ~14 V (BATT- to BATT+) w/ engine running.

A few photos would have let us answer right away w/o speculation. Many posts here w/ good photos on both early and later charging systems. Search Google Images.

Other possible culprits... bad battery and/or jump starting, or simply bad battery cables.
Years ago a friend had a Nova that repeatedly tossed its charging system, alternator, voltage regulator, or both.
At 1st glance I noticed loose wound electric tape at the end where ground cable lug attached to block. A slight tug and it came right apart. One new cable and another regulator is all it needed. I went ahead and installed the later delco alternator with regulator inside. No more problems. And check that the ground strap from firewall to engine block is securely in place.