Hi ,If ok I would leave alone … if you see evidence of melting get into it .many of them did fine , but really a marginal design . Disturbing them may do much more harm than good. —-If happy leave it alone . I did not mean to instill worry , in our club over this , but a high % do go bad ; it may be that people add more powerful replacement alternators from later years , over 50 years now of maintaining , thus stressing the bulkhead connection even more . The original alternator worked fine at 35/ 40 -50 A for so many years , —so , thinking a 70 + is better etc = May be lame thinking . And burns up the connector . I have had 3 different 70’s dodge trucks burn up the connector , and a “ restored” by others 67 cuda 340 , restored with a later “ better” alternator , and my 67 dart convert . But AC equipped 57-59 and 300F (only a 40 a generator , even on AC , with no bulkhead connector ) never , ever melted # 12 or # 10 stock wires . Generator has a current regulator , 35 or 40 A alternators do not . Inherently regulate at max rating . Same with 60 and up . Cannot say stock won’t fail , say melt or deform at 60 A , but in real everyday world the stock wires seem ok . I have never seen overload melt , but have seen short circuit burn up the harness twice ( F and G )
Also the 40 A source from original alternator or generator is obviously ok. It worked for first ten years, kept up with AC and headlights / wiper …
The problem may come with a large “group 27 “ battery that is dead , and a 60 A or more alternator “ upgrade” that charges at a higher than 40-50 max design rate . Conjecture , —but possible it burns or overheats wires , as a previous poster mentioned ,—— For sure it will rapidly hurt the ~ 25 A real rating bulkhead connector . Damage is obvious — it is melted . So , your mileage may vary !! Don’t overthink it , if working fine … AC or not . But adding fuse or fusible link at starter relay is good protection . A burned harness is a true disaster , cars were junked over that .. ** hope this helps , John Ps on headlights you may have upgraded wattage halogen lamps ( I do too ) which really need a relay pair , as the breaker in the headlight switch may open and close as the protection device if more than normal current flows . Check out LMC truck halogen upgrade ( H 4 , not sealed beam ) you can put 100 watts in . I use 80 W hi beams but you have to use relays . ( kit sold by them) BMW blue hi beams will get the message . LED hi beams not worth cost and complexity , and I don’t like blue light . Stuff that breaks , not the LED but supporting electronics ( and $) J ** I remember a cartoon “ have you driven a Ford lately” script underneath it , showing a fried guy in drivers seat of a flamed out Ford , when their ignition switches shorted out, set car on fire . Led to fusible link at the battery supply , after a major recall of burning Fords . Still makes me laugh .. cartoon may have been in New Yorker . Sent from my iPhone On Nov 20, 2022, at 6:17 PM, D.C. Mason <petergriffinforpresident@xxxxxxxxx> wrote:
Hi John,
Along these lines, for our 64, do you recommend i remove the bulkhead connectors and clean them or let them be? The wires are a bit stiff that’s why I ask. So far no troubles I know of, except when using high beam lights after a few minutes they will turn off or blink on and off. On low beams no problem. Headlight switch already been replaced as well as foot dimmer switch….
Thanks! D&K Sent from my iPhone
Begin forwarded message:
From: Ray Jones <1970hurst@xxxxxxxxx>
Date: November 20, 2022 at 2:06:22 PM EST
To: John Grady <jkg@xxxxxxxxxxxxxxxxx>
Cc: James Douglas <jdd@xxxxxxxxxx>, chrysler 300 club <chrysler-300-club-international@xxxxxxxxxxxxxxxx>, Ray Jones <1970hurst@xxxxxxxxx>
Subject: Re: {Chrysler 300} Bulkhead Wires, over heating issues, typical of 1960's MOPAR -Wonky technical discussion.
Several things I didn't see mentioned. On EVERY car with Bulkhead connectors, pull them apart and clean ALL the connections. - On the male prongs, use pliers to give them a 15° twist. This ensures they will have a good connection in the female part.
- And for some who are not sure what a relay does, it uses a little current to make a switch inside the Relay close, which allows a large current to flow. This prevents a Dash switch or connectors from overheating and/or burning out.
This works well for heavy energy users such as Horns and headlights, as well as for the above mentioned uses.
Hope this helps, Old Ray
James , All the current charging or discharging the battery eventually passes through the wire at the Starter relay main feed. That is where a single protective fuse goes . Or fusible link . There is absolutely no need for fuses or relays in parallel wires from alternator etc . Think how any given stock car is wired . Whether it is two 12 in parallel ,good for 50 a at least— or one #8 , the electrical current does not know a #8 is cut in half lengthwise to make two #12 or is intact as a # 8 . Way overthinking and over complicating a simple thing , run a single parallel wire alternator to starter post , connect to the existing 10 or 12 car feed there , run both of those through your fuse to + post . Parallel two 12 or an 8 to batt terminal feed post , or use a fusible link . Done . 50 a fuse . Ammeter will read a bit low , due to parallel path does not matter . In fact it maxes at 30 or 35? so - what if you did run 60 ! It would peg! Many have no scale anyway . Main thing is if charging or discharging . John Sent from my iPhone
I have been having a discussion with a bunch of the people I know who know something about electrical circuits. A couple of things has come up. One of them is the issue that parallel circuits tend to have LOWER resistance than the sum of
each individual circuit. This is a good thing if one runs a parallel wire to each of the number 12 factory wires rather than just replacing them. The downside is that if you fuse both the old and the new you risk the possibility of allowing way too much current
through the wires if there is a shot. They confirmed what I thought on this.
I agree with everyone that talked about the importance of all the connections to be Clean, Dry, tight and Deoxidized. I go through those little $30 cans of DeOx on a regular basis.
Assuming all the above, I think that my preferred solution is not a bad one. Take the two #12 wires out of the bulkhead connector and run them through a mega fuse holder and pick a fuse with the correct current and time delay for the protection
needed. Those calculations my take me a few days. I have to read up as it has been decades since I studied that in detail. The new #10 wires will be installed with relays fed from the factory #12 wires. I could place fuses in the #10 wires as long as they
are before the relays. That would guarantee against any issues.
The one thing that was pointed out to me was that if I wanted to provide a path around the AMP meter is that I could jump my #10 wire from the Alternator to the Starter Relay Battery Stud and so if the battery needed to draw a lot from
my PowerMaster 90 Amp alternator it would provide another path. I just need to fuse the jumper as well.
I know this seems like over kill. But, since getting NEW 35 AMP alternators is tough and I want that 40 or so AMP at idle and stop and go traffic in the rain, at night, with everything going….
The real issue will be making a block that I can mount on the drivers side fender that would hold neatly the fuses and the relays.
James
There has been some thoughtful dialog on this subject and I hope this adds to the knowledge/experience base. During the restoration of our 300K conv with air, my technician
was working on the RH door power window with the engine off. Smelling smoke, he quickly disconnected the battery but discovered the bulkhead connector had melted around the area where the #12 wire from the battery passed through the bulkhead connector and
allowed the hot wire (!) to short out to several other wires. My perception was that as the battery Voltage dropped, the current needed to operate the P/W motor increased and that current/power for the most of the car’s electrical load normally came through
the bulkhead connector on the wire from the alternator and when the engine was running. Further, the 30 Amp circuit breaker that protects the power seats, power windows and power top did not open so the current was probably under 30 Amps. The problem arose,
partially due to a poor connection at the bulkhead connection on the hot wire from the battery.
Lessons learned Inspect the bulkhead connections by removing the two 8-wire connectors from the bulkhead connector under the hood. Clean and polish any corroded/oxidized connectors,
especially the two #12 connections of the #12 feed wires (black & red). Do not operate the power top, power windows or power seats with the engine off.
Whilst shopping for a replacement bulkhead connector it appears the similar ’63 Chryslers ran these two #12 feed wires into the ammeter via a copper bar through the plastic
with screw terminals for ring connectors at least on the engine side. The ’64 wiring diagram indicates a 40-Amp fusible link was an option—likely for police & taxi service. I don’t see this adding much protection for an under-designed bulkhead connector
with the same Packard connectors for 20-30-Amp service as the much smaller loads for lights, ignition, horn relay, washer pump, compressor clutch loads under the hood. I don’t see that A/C adds that much load, but mebbe so. BTW, anyone ever seen a ’64 Enforcer
police car? Or a ’64 Chrysler taxi???
A conservative fix would be to get current in and out of the passenger compartment via an alternate route. I like the idea of soldered connectors passing through separate and
nicely. grommeted new holes in the firewall. Maybe pass fusible links through the firewall and solder in each end. Lacking soldering, add a short terminal strip with ring connectors on one or both ends.
And, yes, most MoPars of this age do not experience this issue—but it is too common of a problem to ignore. Nowadays it might justify a recall.
Be careful out there. Keep these beasts alive.
Rich Barber
Brentwood, CA
I have been reading up on the issues with bulkhead wires melting down. My old 1964 300K CV had that issue when I purchased it and it did not have A/C.
There are several different approaches to the issue. I have read over several of them on the internet. I have also talked to a friend who is EE.
I am interested in a nondestructive approach that would deal with the issue. This car has AC and will be driven daily in the Central Valley of California and at our place in San Francisco a 1000 yards from the pacific as well as cross country
this spring and summer.
What I am thinking of doing, and if you are not very familiar with electrical theory then just close this message, is to add two load bypass wires; a shunt of a sort.
The problem with just adding a couple of wires run through the firewall, like Chrysler did on the police version of the cars, is that if something draws a big load the factory #12 wires could still melt in the bulkhead connector.
My idea is to add a #10 wire to each side of the AMP meter. One would run to the BATT side of the Alternator just like the factory wires does and one to the starter relay just like the factory wire does. For 1964 that would be the R-6 wire
and the A-1 wires. My wires would parallel the factory wires.
Now the issue is how to protect both the existing bulkhead wires and all the other harness wires in the event that something draws too much current through those new #10 wires. You cannot fuse both sets of wire as that would almost double
the available current to say something like the AC or headlights.
What I am proposing is to pull the two existing #12 wires out of the bulkhead connector on the engine side. Then route each one with a short wire to a MAX Fuse block. Then route them back to the original mating bulkhead connector. Then
on the protected side of the MAX fuse block, run a hot feed to a high current 12 volt relay. That relay would control when and if the new #10 wires were in circuit. If the fuse goes it would cut the power not only on the factory #12 wire, but would open the
#10 wires via the relay as well.
Such an arrangement would be totally reversable and not cause any cutting into the harness. I would have to play with the fuse size. Those factory #12 wires theoretically are only rated for about 30 AMPS. The factory alternators were 30
to 50 AMP. Not good especially with that crappy bulkhead connector.
I suspect I will have to start at about 40 AMPs and see what I get on a rainy night with the AC on to defrost, the headlights on high, the fan on high, the rear defroster fan running, the radio on and the like.
Any Electrical Engineers on the list who want to chime in?
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-- Ray Jones. Y'all come on down an see us. Ya hear?
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