Hello all, I just bought my first slant 6 powered ride, a 1965 Valiant 100 and had a question for you all. I noticed that the headlights dim under any sort of load (windshield wipers, turn signals etc) and seem to flicker a bit when the car is at idle. I haven't had the chance to test the alternator yet, but does anyone have any ideas on what to look for?
Thanks!

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Killing the planet, one tank of petrol at a time

The stock alternator is only 35 amps.

So under those conditions it's normal for the alternator to not keep up with the load.

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Welcome to the wonderful world of OLD Mopars. As stated above the charging system was barely ok when new. Look at your electrical system VERY carefully. I would go over every inch of it looking for cracked wires and corroded terminals, check the bulkhead connector and the amp meter carefully.
Then start upgrading the electrical system ( use the search function) or look at the top of this section and check out the FAQ Sticky.
Frank

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Scrapple: Because a mind is a terrible thing to waste.
73 Duster - Race Car
66 Dart Wagon - DD
178" FED
82 D150
All Slant powered

Heck ,, with the blower on, full wipers on,headlights on, and your foot on the brake you'll think the whole system is going into meltdown. As stated above,,, Normal. That was the biggest complaint we had at the dealership on the slant six cars when new... OH, I forgot the radio on too.

Welcome on the board. The problem has nothing to do with the original alternator's 35-amp rating, which was plenty (do the math, Ed) to keep up with the load of headlamps, heater blower, wipers, radio, and ignition all at the same time when the alternator, regulator, switches, and wiring were all new. The only problem was that the alternators, even when new, didn't produce anywhere near their max output at engine idle speed. Now, forty-five years later, there are additional problems: the wiring and connections are old, and have higher resistance than when they were new. The alternator has very likely been replaced, probably with a thrown-together "remanufactured" unit that has even poorer low-rpm charging than the original. The voltage regulator is also old and no longer as quick or efficient as when it was new. The whole electrical system relies on grounds through body sheetmetal; these were (barely) okeh when new but they're no longer new. The ignition switch, headlamp switch, high/low beam switch, wiper switch, and ammeter (through which all the current in the car passes) are old and have high internal resistance. All of these factors add up to create the problem.

Fixing it will require careful, systematic work. You will likely want to get a new alternator, but do not just throw a higher-amp alternator in there. It may appear to solve the problem, briefly, but it will quickly cause extensive and expensive electrical system damage.

So before you make major decisions like how much money and effort you want to put out and what level of charging system performance you want to wind up with, start with the relatively easy stuff. Carefully inspect each and every wiring terminal you can get access to, including the ones at the multi-wire connector on the firewall. Clean those that need it, use small tools to re-form deformed connectors that will tolerate it, and replace those that cannot be cleaned or re-formed. Purchase and apply Stabilant 22a (see here and here to each and every connection, including those on the headlamp switch and on the high/low beam kickswitch. Install a new voltage regulator, Standard-BlueStreak #VR-128 or NAPA Echlin #VR-1001. Run a ground loop of 12ga wire from the alternator housing to the voltage regulator base, and from the voltage regulator base to the battery negative terminal.

Next step is to have the ammeter upgraded to handle higher charging system current.

Then you need to decide whether you can tolerate a little dimming and blower slowdown at idle as long as the system keeps up overall (less costly alternator) or if you want to eliminate every trace of dimming/voltage sag at idle (more costly alternator, bracket modifications).

Replacing the headlamp and high/low beam switches wouldn't be a bad idea, to reduce the voltage drop their old, small contacts are inducing. Putting in headlight relays gives better results. See here and here.

All of this is something of a nuisance, yes, but everything will work better once you've done it. The engine will run better since the ignition's no longer starved, the lights will burn brighter, radio will be stronger, etc.

Additional info on testing and repairing charging systems is here, here, and here.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

My radios went out on two different Mopar products & were corrected by cleaning the contact areas for the ground strap between the engine and the firewall.

My current 65 Dart has the strap mounted at the back of the head. It is partially hidden from view but is accessible.

On one car the ground strap was flat woven wire that might be equated to a 4 ga wire size. On the 65 Dart it is round & covered (moisture protection?) & at least 10 ga.

You might find this strap missing or not connected if the engine was ever removed.

The extra ground Dan is suggesting from the alternator to the voltage regulator & over to the battery terminal might provide a similiar function as the above ground strap?

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1965 Dart 110k, 225, Carter BBD Super Six, 2 1/4 single exh., sbp manual scarebird front disc, 7 1/4 rear 2.94 sure grip, 14 x 4.5 OEM wheels, 833 OD with hyd. throwout bearing, HEI, electric fan, ram air/heated air, Accusump. http://plymouthcarclub.com/

Similar, but not interchangeable. You want both.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

this dosn't seem quite normal. At night, my lights are all but off, and i can't see the gauge lights at all. Also, turn signals are inop. When i'm on the freeway however, everything seems more or less copacetic. I know my battery is quite old, and plan on replacing it tommarow, but any ideas on where to start? I don't have a Voltmeter, but i might be able to borrow one.

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Killing the planet, one tank of petrol at a time

Start by buying the three books described in this thread. Your car has electrical problems, but if you dive in and start trying to fix them without knowing what you're doing and how to do it safely and properly, you will make the problems bigger and more costly.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

found my issue, a wire left from the P.O.'s stereo install was grounding itself against the inside of the dash, I removed it, and presto! no more dying lights.

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Killing the planet, one tank of petrol at a time

I did the 120 AMP Diplomat swap as described in http://www.slantsix.org/forum/viewtopic.php?t=28160 All I can say is WOW!
The bracket modification wasn't quite as easy as described, I had to weld up a spacer for the upper bracket so it would clear the fan, but the lower bracket was pretty simple, just grinded a small bit off the front.
Also had to swap belts to make the upper mount fit, i can get part numbers if anyone needs them.

No more flickering headlights, thats for sure!

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Killing the planet, one tank of petrol at a time

Hope you upgraded your charging circuit and ammeter as described here, or at least ran the output directly from the new alternator to the battery, or else you're fixin' to have a big electrical fire.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I just did the quick and easy way for now, running the B+ to the battery, plan on putting in a volt gauge at some point

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Killing the planet, one tank of petrol at a time