Flickering Dash and Headlights '66 300

[Justin Heydon]

Hello All,

Just finishing up some final touches on an engine bay restoration on my '66 300 convertible with A/C. We took it for a test drive last night and the dash and headlights were flickering and the ammeter was jumping around fro discharge to charge in conjunction with the lights flickering.

We completely redid the wiring inside the engine bay and followed the service manual schematic for wire sizes. We also replaced the alternator and voltage regulator. The alternator was purchased from advanced and is rated for 60 Amps.

Could one of these two items already going bad?

Please share any tips or ideas.

 

[BigblueC]

Could one of these two items already going bad?

I'm pretty sure that's your VR going out. Part store parts are just junk in a new box.

 

[Ripinator]

Hello All,

Just finishing up some final touches on an engine bay restoration on my '66 300 convertible with A/C. We took it for a test drive last night and the dash and headlights were flickering and the ammeter was jumping around fro discharge to charge in conjunction with the lights flickering.

We completely redid the wiring inside the engine bay and followed the service manual schematic for wire sizes. We also replaced the alternator and voltage regulator. The alternator was purchased from advanced and is rated for 60 Amps.

Could one of these two items already going bad?

Please share any tips or ideas.

If the problem is due to a marginal VR, you should check with @FURYGT . He sells a really good and stable electronic VR that is not expensive. I run one in my '66 convertible.

 

[C Body Bob]

Check your grounds

 

[traintech55]

Nine times out of ten it is the points inside the mechanical regulator hunting, an electronic one will cure most of it, I have also seen a bad ammeter gauge contribute to this problem, (I have to replace the one in my 66 300). good luck.

 

[dart4forte]

Another mod to consider is a wiring harness that member Crackedback sells. It runs the HLs through relays. Really clean mod, simple to install. Your lights will be much brighter as well as your dash lights

Crackedback usually hangs out on FBBO or FABO

 

[BLUPORT]

...or the switch itself has dirty contacts? Work it on and off and see if that helps at all. Purely anecdotal, but that was the issue with my car.

 

[cbarge]

Original alternator is rated for 35 or 38 amps. Your parts jobber is almost DOUBLE that!!!
You may as well toss the FSM into the fire once the car burns.
Ok. Relax...I got this....
Upgrading your alternator is a good thing but MUST UPGRADE WIRING TO MATCH.
1. Run an 8 or 10 gauge wire from the battery stud back of alternator and run it to the battery stud at starter relay. Use a 12 gauge fusible link or 20 inline fuse at the relay end for easy future repair.
2.Do the bulkhead bypass!
3.Putco makes a plug n play headlight harness that includes relays. No hacking of original lighting harness.
4. For the sake of cheap replacement, get a new headlight switch and foot switch.
5. Double check ground wire for headlights typically bolted to rad core support driver's side. Clean it up if needed.
Hope this helps.
I did all this on many cars including a 66 300 sedan.
Cheers

 

[70bigblockdodge]

If it is a even pulse at idle it may be the rectifier or diode group depending on weather you have a square or round back alternator. Yours from the description sounds like the voltage regulator.

 

[Justin Heydon]

Original alternator is rated for 35 or 38 amps. Your parts jobber is almost DOUBLE that!!!
You may as well toss the FSM into the fire once the car burns.
Ok. Relax...I got this....
Upgrading your alternator is a good thing but MUST UPGRADE WIRING TO MATCH.
1. Run an 8 or 10 gauge wire from the battery stud back of alternator and run it to the battery stud at starter relay. Use a 12 gauge fusible link or 20 inline fuse at the relay end for easy future repair.
2.Do the bulkhead bypass!
3.Putco makes a plug n play headlight harness that includes relays. No hacking of original lighting harness.
4. For the sake of cheap replacement, get a new headlight switch and foot switch.
5. Double check ground wire for headlights typically bolted to rad core support driver's side. Clean it up if needed.
Hope this helps.
I did all this on many cars including a 66 300 sedan.
Cheers

The alternator I have is 60 amp. Is that too much that I'll never get this resolved? Where could I find a lower output?

 

[cbarge]

The alternator I have is 60 amp. Is that too much that I'll never get this resolved? Where could I find a lower output?

If you read my post correctly, I explained how to keep the alternator you have and upgrade your wiring

 

[cbarge]

From Autozone get a VR706 regulator. Fully electronic and can handle the 60 amps.
Your old mechanical regulator cannot handle the 60 amps.
Best Voltage Regulator Parts for Cars, Trucks & SUVs

 

[cbarge]

You can pop your old VR cover onto the new electronic regulator...

 

[cbarge]

Headlight harness with relays.
Heavy Duty Wire Harness & Relay
For our C's I use part #230004HW
Plug n play and really works taking a load off the headlight switch and foot dimmer switch.

 

[BLUPORT]

Headlight harness with relays.
Heavy Duty Wire Harness & Relay
For our C's I use part #230004HW
Plug n play and really works taking a load off the headlight switch and foot dimmer switch.
View attachment 282463

I'm considering doing this upgrade myself. My lights have started flickering again. I am going to replace the hi beam stomper, and if I can find the actual dimmer and headlight toggle somewhere without breaking the bank, then I can start driving at night.

 

[LocuMob]

I'm considering doing this upgrade myself. My lights have started flickering again. I am going to replace the hi beam stomper, and if I can find the actual dimmer and headlight toggle somewhere without breaking the bank, then I can start driving at night.

I tried that in my car to no avail. It either worked or didn't, at least in my case.

 

[cbarge]

I'm considering doing this upgrade myself. My lights have started flickering again. I am going to replace the hi beam stomper, and if I can find the actual dimmer and headlight toggle somewhere without breaking the bank, then I can start driving at night.

Typical 68 chrysler issue...headlight switch circuit breaker gets old and trips out.
The harness with relays cures that.
Period.

I have spare headlight switches but need part number off yours. To the naked eye they look the same but different.

New foot switch is cheap insurance.

The dimmer switch for dash/dome lamps are an expensive item whether nos or rebuilt. No new ones available. The B body crowd has driven them up in price (same switch).
You can buy a rebuild kit and fix it yourself. Most just need good cleaning and freshen up the soldered points

 

[BLUPORT]

Typical 68 chrysler issue...headlight switch circuit breaker gets old and trips out.
The harness with relays cures that.
Period.

I have spare headlight switches but need part number off yours. To the naked eye they look the same but different.

New foot switch is cheap insurance.

The dimmer switch for dash/dome lamps are an expensive item whether nos or rebuilt. No new ones available. The B body crowd has driven them up in price (same switch).
You can buy a rebuild kit and fix it yourself. Most just need good cleaning and freshen up the soldered points

My dimmer was pretty wonky at first, but I gave it a couple rounds of the old "back and forth" and it works great now. It's just the flickering of the actual headlights, they will actually go completely off, but if I lightly touch the switch, they come back on.

Once I finish the trunk, I plan to move on to the dash, and I'll get you the P/N. I'm assuming that whole bezel needs to come off to get to it.

 

[jct]

Yes it does along with lowering the steering column

 

[BLUPORT]

Yes it does along with lowering the steering column

Oh joy. Well, I need to get back there to replace the bulbs in my gauge cluster anyway, as well as to get my dash pad off, so I'll just bump that whole thing farther down the list of priorities.