67' Barracuda Alternator Charging Problem

[Guest]

I have a 1967 Plymouth Barracuda with the 273 and electronic ignition. Ever since I bought the car several years ago the alternator gauge needle reads to the left of midpoint at idle. It gets worse with any accessories on and the headlights dim substantially. It is definitely unacceptable. The charging voltage reads outside of specifications at idle according to a voltage meter hooked to the voltage regulator. The alternator gauge needle moves to the right of midpoint with acceleration. This type of gauge movement has always occurred on other old Chryslers I've had before but to a much lesser extent. I upgraded to the 1970's type voltage regulator for electronic ignition and the alternator with the extra terminal but the problem persists. Recently, I was driving when the alternator gauge pegged out on charge. Now the alternator gauge reads at a much more acceptable level at idle even with accessories on. However, the alternator gauge needle moves towards charge with acceleration and pegs out on charge at about 2500 rpm. I can't figure out what the problem is. Help!

[52deluxe]

my 1970 dodge d200 crew cab was doing the exact same thing, turned out the alternator and voltage regulator were bad. i replaced them both "they are real cheap" and it works fine now. you can always take the car to autozone, partsamerica, or some other parts store as many will check your charging system for free.

just a thought

tom

[decembro]

Check your grounds. You may have a corroded or loose ground wire. Could be engine ground, body ground, or dash ground. And, although your grounds could be tight, take them loose to make sure you're getting good contact with "real" metal. Sometimes fenders etc. are painted and then the wires are attached and therefore you still don't have a good ground. You can't count on the screw threads to complete the circuit. A great investment is a package of star washers available at Home Depot or any hardware store. Get an assortment and place the washer between the eye terminal of the wire and the grounding surface. They are designed to dig into the metal making a good contact. Good luck.

[decembro]

I am assuming the belt is tight and you can't move the alternator by hand (with the engine OFF!!!)

[warlock]

I agree that a bad ground probably causes the high charging rate. Most likely at the voltage regulator. The low charging is unfortunately a mopar problem. I solved mine by putting a larger crank pulley from one of the junks out back. No lower reading at idle as the larger pulley turns the alternator a little faster. I have also heard of the corrosion at the firewall, as mentioned earlier, as a low reading problem, but haven't encountered it myself.

[NTX5467]

The "Alternator" gauge is reading amps instead of volts. GM started the whole thing with the "Volts" instead of "Amps" to indicate charging system status in the early 1970s. There are reasons for both approaches.

The alternator you installed has no significant extra output, even though it has an extra output terminal. In using that alternator on an older vehicle, there should have been some instructions on tying the two output terminals together with a piece of wire. The basic reason for that extra output was to drive the electric assist chokes that were used beginning in the early 1970s, thereby making it easier to adapt the wiring harnesses than to design complete new ones. The later 1970s alternators had better cooling (the ones with the waffle shaped grid on the back of the alternator) but no real significant increase in alternator output. The 100amp models that were used on the middle 1970s cars with electric back window defroster were much bigger in case size and took different mounting brackts, similar to the police car equipment Motorola alternators.

Of course, as mentioned checking all of the alterator connections to make sure they are good is very important for max alternator output. So is having clean and solid battery cable connections too--even if they look acceptable, there can be some gunk that can be hidden between the cable end and the battery post (which can still show normal voltage but will not let enough amps through for things to work right). While you're checking voltages, make sure the battery cables are not "eating" any voltage too.

Seeing the lights dim at idle on a Chrysler product of that vintage is somewhat normal, but still disconcerting when it happens. I have even noticed similar things on my '77 Camaro, though, but it was minimized when I went to a larger capacity battery on the Camaro. The "normal" replacement battery (using CCA as a guide) would be a 75-5YR battery. When I went to the higher CCA 75-6YR battery, the problem diminished some and is not nearly so noticeable (usually when the vehicle is first started and backing out of the driveway).

The electronic voltage regulator is not a sure fix for the problem either. It's main function was increased durability and reliability. I certainly hope you used an OEM replacement and NOT the one that Mopar Performance sells for the earlier systems as there are critical differences in the voltage levels that can cause other problems (which I found out about when I used one, and later read about "why" it happened in the Direct Connection Engine Manual). When the older points-type regulators are working correctly, they worked just fine and well enough to support the Mopar Performance electronic ignition conversions. The older regulators can also be adjusted too, if you follow the instructions in the Chrysler service manual.

The reason for the Mopar Performance/Direct Connection specific voltage regulators having their higher basic voltage range is to support the "Orange Box" electronic ignition control module's need for higher than normal voltage to even fire the plugs. I've seen some cars with that control box that would spin over just fine, but not fire the plugs until a jump was received from another vehicle. The stock control box does not have quite so high a minimum voltage threshold to fire the plugs, but is still more than it would be for a points ignition system. As the race manual noted, using that higher voltage electronic regulator CAN affect the life span of ALL electrical parts on the vehicle. In my case on a '67 Newport, I found all sorts of flaky wiring connections that a previous owner had installed--resulting in sudden engine stoppages or no starts after it had been running, not fun.

In some respects, you are seeing a somewhat normal condition on earlier Chrysler products, but you can possibly minimize what's happening by checking the things that have been mentioned. Problem is that once you notice it, you tend to key on it and think it's a malfunction getting ready to happen, which might not be the case.

Be sure to check the firewall bulkhead connection block for poor connections as that's part of the charging system circuit too. The voltage spike you mentioned could usually only be from a shorted wire or similar that would suddenly cause a need for higher amperage output from the alternator.

Hope this helps,

NTX5467