Basic question on a complex rewire (for me)..

[RuNvS69]

Hi guys,

 I'm completely rewiring my 70 Charger 440 and yes I have used the search feature, used google and spent HOURS researching/buying everything.

The facts:
-Brand new repro engine harness and forward light harness
-MSD Digital 6AL box
http://www.summitracing.com/parts/msd-6425
-MSD Pro Billet Distributor
http://www.summitracing.com/parts/msd-8546
-Quality Power 150amp 1-wire *INTERNALLY REGULATED* alternator (NO field wire connections, only power output)
http://www.qualitypowerauto.com/catalog.php?item=557
-BeCool Aluminum radiator setup with Dual Fans/relays
http://www.summitracing.com/parts/bci-82260



The issue:
-Alternator power wiring...  The repro harness appears to have a standard #10-gauge black wire that goes from the alternator output into the bulkhead connecter.  I am aware that I need to run a #6-gauge wire from the alternator output over to the battery stud on the Starter Solenoid... but what about this black #10-gauge wire?  Connect it to the alternator output as well or remove it completely from the system?  I assume I need to connect it with the new #6 gauge wire because it probably still needs to feed to the rest of the car.  Am I correct?

**On a side note***  My car was originally a 2-field wire alternator system so I am completely removing the ballast, regulator and ECU and then cutting the BROWN wire and the BLUE w/ WHITE STRIPE wires that come out of the bulkhead and splicing them together.  I will also splice in the small RED MSD wire with those two since it is a "keyed power source".  Ammeter will be bypassed simply by splicing the two wires together behind the gauge.  Both BeCool fan relays will have their power wires connected at the same battery stud on the Starter Solenoid.  

Am I missing anything else here??  Should I upgrade the wiring to the starter motor as well?

MANY THANKS TO THE PRO'S!
 -Tim

[Pete in NH]

Hi Tim,

On the alternator wiring, I would just tape back the harness black 10 gauge original alternator output wire and not use it. Your new #6 gauge wire from the alternator output to 1/4 inch stud battery wire will take care of that wiring path. Connecting that #10 black wire will only take you back up through the bulkhead connector which you want to bypass anyway. To feed the rest of the original car circuits, connect the #10 red wire in the harness through  a 50 or 60 amp maxi-fuse blade type fuse to the same 1/4 inch battery stud on the starter relay. This will take the place of the original fusible link path to the ammeter which you are bypassing. You could also run a new #10 red wire from this new fuse directly to the black wire splice point that was connected to the ammeter. This will bypass the bulkhead connector entirely.

The power to you new fans from the battery stud should also have its own fused circuit. Check the current requirements for the fans and use the indicated fuse size.

I don't think you need to do anything with the existing starter wiring unless it's poor condition.

[RuNvS69]

Hi Pete-- THANK YOU!!! I've read that some have used the original #10 black alternator power wire and just doubled it with another #10 wire to handle the increased power load but I'm running a pretty heavy duty alternator and think that a single #6 gauge should be more than enough.

Can you clarify just a bit more on the red wire though?  So the #10 red wire you're referring to from the bulkhead is actually found on a different bulkhead connector than the main engine harness I'm working on now, correct?  If I'm bypassing the ammeter behind the dash are you saying I should cut the #10 red wire and fuse it then run it straight to the battery stud on the starter relay?

I'm really just looking to make this the cleanest/most simplistic wiring install possible as I've put a LOT of money into new parts and I don't want to have a bunch of clutter in the engine bay.

BTW-- I'm in NH too! Maybe you should come take care of this for me, haha

[RuNvS69]

The BeCool fan kit and wiring is TOP NOTCH... and it better be when it costs $1,600 for everything! It includes separate harnesses/relays/inline fuses for each fan:




Here is the small red MSD wire and the brown and blue/white stripe wires I will end up splicing together:


What's under the electrical tape of a new YearOne repro wiring harness?  Soldered/heat shrunk connections?  NOPE!


....a crimp.   

[Pete in NH]

Tim,

I'm in the Lakes Region, where are you in NH?

On those Year One wiring harness connections only being crimped together, you might want to consider doing a little soldering while they are still new, bright and shiny because they won't stay that way over the years.

In one of your pictures there is a light blue "wire" right off a bulkhead connector pin with a yellow molded tag "fuse link" that is the red wire point I was talking about. On the other side of the mating bulkhead connector pin it goes to the ammeter. You might want to consider just not using that connection and running a #10 red wire directly through the firewall to the "splice joint" on the other side of the ammeter. A 50 or 60 amp blade fuse right off the 1/4 inch battrey stud starter relay connection where that fusible link in the picture would go.

[RuNvS69]

I'm in southern, NH-- not far from Manchester 

Based on these pics I can see what you mean about modifying the feed lines. 

OLD:


vs.

NEW:



I like the idea of completely bypassing the bulkhead connectors WITHOUT drilling through them (as I can just run the lines through a grommet in the firewall next to it). 

A few thoughts:
  -It looks like if I tape off the old alternator wire in the engine bay, I better make sure to cut it before the "welded splice" inside the car or else it will become a live wire just sitting in the engine bay as it milks power from the circuit for the *fuse box, *light switch and *ignition switch. 
  -Instead of taping it off though, I COULD cut it and splice it into the new #10 RED wire you mentioned I should run from the relay to the ammeter splice and that would save me some time.  But then I'd have bypassed only that blue power wire/bulkhead connection and I'd still be relying on the black/old-alternator bulkhead connection.

Maybe I should just start from scratch and run both new #10 gauge wires as depicted in the second pic and be done with it.  Cut off/remove the old alternator line and tape off/don't use the blue fuse link line...

Decisions, decisions...

[MaximRecoil]

What's under the electrical tape of a new YearOne repro wiring harness?  Soldered/heat shrunk connections?  NOPE!


....a crimp.  

A crimp is exactly what it should have there. Note how factory-original wiring harnesses have no soldering, everything is crimped (and over 40 years later, all of the factory crimps in my car's harnesses are still fine). Solder is relatively brittle, and a car environment tends to have a lot of vibration. This vibration can crack solder joints over time. Hell, even without vibration solder joints can crack over time, just from expansion and contraction from changes in temperature (and a car environment tends to be subject to large temperature changes). You'll see plenty of cracked solder joints if you spend any time repairing old TVs and arcade machines (or PCBs in cars, like the ones powering modern instrument clusters).

A proper crimp on the other hand is flexible. It is also airtight, which prevents corrosion from forming on the wires contained inside the crimp. Solder has absolutely no advantage over a proper crimp in this application, and it has the downside of being brittle. And it is not just the solder that is brittle; when you solder e.g. copper wires, it forms an alloy with that copper, and when the solder breaks, it will break the formerly flexible, but now brittle, wires in the joint right along with it.

Think about how stranded wires work in the first place. Those strands all conduct electricity through each other simply by touching each other tightly; they are obviously not soldered to each other. Think about how all your grounds are formed; usually a ring terminal held tightly to a piece of steel, not soldered. Your battery post terminals, same deal. A proper crimp works on the same principle, and is strong enough that you will tear most of the wire strands off before you'll ever pull a wire out of properly crimped connector.

That soldering is automatically superior to a proper crimp (or that a joint that is crimped and soldered is automatically superior to a joint that is just crimped) is one of the biggest misconceptions I see on the internet. And don't think I'm saying this because I don't know how to solder, or don't understand soldering. I worked for 2 years in a PCB factory inspecting and soldering ~1000 boards a night using a Metcal MX500 solder station (I also own a Metcal at home). I am SMT certified and I also trained new-hires to solder at that place. Soldering definitely has its place (e.g. PCBs, plumbing), but a car environment isn't an ideal place for it.

[RuNvS69]

That's a hell of a write-up on crimping vs. soldering! 

Any thoughts on my wiring plan?

[Pete in NH]

Hi Tim,

You're about an hour or so south of me, so we might get a chance to get together someday. Your diagram B is exactly what you want to do. Yes, do disconnect the original black alternator wire from the "weld splice". Yes, as I mentioned you might just want to run the new #10 red wire from the battery feed stud through the firewall directly to the weld splice and eliminate all the splicing around and ammeter terminals connected together. That would clean up the wiring greatly.

MaximRecoil, all you said is absolutely true. If you have the correct crimping tool for the connector you are using and use it properly you can in many cases get so much pressure on the crimped connection that the metals actually cold flow into each other which is exactly what you want. However, so many crimped connections are not made with either the proper tool or correctly in a home workshop environment that I see crimp and solder as not a bad way to go. I am also aware of the solder wicking issue up a piece of stranded wire and believe the trick is to use just enough solder to get an electrical bond not load the wire up with solder. I'm basing my comments on my experience in the electrical engineering world and know that what can be done ideally in a production environment and what happens out in the field are two very different things. I've seen a number of badly crimped connections fail over the years, more so than so, so crimped connections that were also soldered. Soldered connections are only going to fail if they really start moving around. I don't think that will be the case if they are tightly taped in a wire harness. I don't see soldering as automatically superior to a proper crimp, it isn't. But I do think it's better that a marginal crimp with the average home crimping tool.
Just my opinion and we all know what opinions are worth!

[MaximRecoil]

Pete, solder is definitely better than an improper crimp. I obviously can't inspect the crimp in question just by looking at the photograph that was posted, but I would guess that YearOne harnesses are made in a factory with proper crimping tools for each type of connector they use. In the PCB factory I worked in, they had bench-mounted automated hydraulic machines for crimping open barrel quick disconnect terminals onto wires (those machines would automatically strip the end of the wire prior to placing and crimping the terminal too), though proper hand tools can be just as effective, such as from Molex, Amp/Tyco, etc.