In its stock form, the battery power (B+12) goes from the battery via a number 12 red wire through the bulhead connector, to the ameter, and then on to a major splice in the harness where a large number of black and red wires, and a few pink ones are joined. I have never unwrapped this splice, and have no idea the quality, or integrity of the splice at this point. From this splice a #12 black goes back out through the bulkhead connector to the alternator. The alternator must pass it's charge chrough the bulkhead connector, through the ameter, and back out through the bulkhead connector to get to the battery to charge it.

To overcome the resistance of old connectors, years ago I took a lead directly to the battery from the alternator. In doing so the black B+12 coming back out from main harness splice wire now becomes redundant. Not only that, but the harness is no longer protected by the fusible link, since the battery is essentially hooked directly to the harness through the black wire since the battery now goes directly to the alternator. If the fusible link blows, the blk b+12 still is connected to the harness.

Keep in mind that the original alternator had a 60 amp output. The present one has 110 amps. So the original #12 Red from the battery to the bulkhead connector is likely not heavy enough. I have two choices. I can up the size of the red b+12 wire from the battery to the bulkhead connector and remove the black wire that originally was the b+12 charging path. Or, I could put a fuse in the black wire, and leave both B+12 paths to the wiring harness. The ameter is no longer present.

If I leave the black wire, what size fuse should I put in the line. According to the MinMopar link that Dan provided, the present fusible link is equivalent to a 50 amp fuse. If I remove the black wire, I am more dependent upon an old, possibly crusty splice in the main harness. But, there was a strong sentiment voiced against redundancy in the wiring scheme. If I remove the black wire, do you think number 10 is big enough for the new red one, and what size fuse should I put in the line in to the harness.?

Also relevant is that much of the underhood power, including the headlight and fan power will get switched on by a relay, and will no longer be powered through the harness, or the ignition switch. The blower motor, radio, windhield wipers, and rear chasis harness will be powered by the main harness still. What do you think? I am still waiting for my wiring book to come from Amazon. So I couldn't help myself from throwing this out there. I finally got my mind wrapped around the circuits present here, so I feel a need to ask this question while I still understand what the question is.

Sam

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Well I'm not an electrician and never claim to be. With that said, I knew nothing of how my 68 valiant was wired until I bought my FSM and began rewiring the engine compartment, due to PO removing Fusible links and burned most of it up. That's when I pulled the dash and seen how the battery/Alt/Ammeter/Ign/etc were all spotsoldered or whatever they call it. It just looks like simple solder to me but also a mess. But 'originally' WITH the ammeter it wasn't redundant but if you bypass the ammeter and just connect to two wires from the ammeter together, then its redundant. I removed my ammeter (no digs at plymouth just my decision, don't kill me SSD). I ran a 10ga from the battery to the starter relay. From there I took a 10ga to the Alt with a maxifuse (just for extra protection) and another 10ga (w/ fuse) through the bulkhead to that solder joint. I didn't want to put the fusible links back in.

I also seen that a 50amp was the right fuse but a guy at my work says that's way too high. But another buddy at work tells me that if you put in a 30amp fuse and have a 45amp alt then its going to blow all the time. Which makes sense but again I am not an electrician and am learning as I go along. Another thing I had to replace were all other wires except for the wiper wiring, which I'm still in the process. But I saw a poster on here, just recently, say his wiring burned up and it was because it was old. So I would go through it and make sure its new, especially with the high amp Alt. Hope any of this helps and doesn't confuse you hehe. -Dan

For safety, you want *something* between the battery and anything else (except the starter). I've seen alternators (through my fault) short out, as well as nearly everything else at one time or another (usually not my fault).

For the Tidewater Mopar Club Fury, I used 4ga for the alt-to-battery run, but the biggest fusible link I could find was #12.

For this ~100A system I used 3 carefully matched lengths of #12 link in parallel and very carefully soldered and crimped the connections and figured that was good enough.

I've not actually tested it out to find out how well it'll work. With luck, it will never be tested.

At best, each link will carry 50A or so
(for a total of 150A) and they'll fail about the same time. At worst, the links will carry slightly unequal currents, and the others will fail in very rapid succession once the highest one lets go.

In my FSM wiring diagram it shows the Battery 10ga go to the starter relay then in through the firewall (that's with the ammeter connected). So basically I have it the same way but without the Alt wiring going through the firewall.

Question, KBB, why use the fusible links when you can use a fuse like maxifuse or something similar? What are the pros and cons of both? -Dan

Sam
Sorry for the delay in answering. I feel that the wire could be left if fuse linked properly. I saying that i would like a rough idea of what add ons you are running thru these wires, ie ,stereo amp, a/c, etc anything not on the car originaly (even things in the works) this will alow me to size /fuse properly.
If you have detailed questions PM me with your phone number and I can call.
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

The actual power that goes through the harness, and ignition switch is lower than stock. The headlights are now run by relay under the hood. The AC is aftermarket, and most likely has a more efficient blower motor than the stock unit. The only added thing is the gauges which would take very little power. There are ten gauges which all have a light, and some unkown load. The radio is a new CD player, but I would supect that the draw is less than the stock unit.

There are two questions here:

1. Should I eliminate the black return to alternator lead which is not needed since I now have a direct alt-batt connection? It seems as if this is truly redundant, and un-needed.

2. Is the original red #12 feed from the starter relay to the bulkhead connector enough? It seems like since the actual reduction in power routing through the harness and ignition switch is lower now, then maybe the stock fusible link is big enough. If I replace this, what size fuse should I use? I have seen none listed as slow blow, anywhere. I Have red #10 wire, so was going to replace the #12 with new # 10

I think I am kind of answering my own question here, but please feel free to chime in.

Sam

Sam

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Sam
Were it me i would remove the black wire. Run that new #10 red and put a #14 fuse link in. I dont think a fuse would be the best idea, especially, in light of the Bad fuses found on the market today. In my cars I have rewired I put a loop outside of the wire loop that is the fuse link so if it goes it doesnt take out the harness.
Hope this helps.
Frank

_________________
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

Thanks for the advice Frank. I will do what you suggested. I guess I will unhook the black wire and tape it off first, and see if everything is still powered before I cut it out, just to be a little on the paranoid, superstitious side.

My basic automotive wiring book came yesterday, and I am studying it. ONe of the more interesting facts about the book is that it used to be in the GM engineer's library in Warren Michigan. It looks like it was checked out only once from the stamp chart in the back page. It is a book designed for the education of repair men, rather than designers, in spite of it's title, Automotive Electrical Reference Manual. I suspect the first design engineer who checked it out, then dissed the book, as it was never checked out again. But I am enjoying it very much. Thanks for the link, Dan.

Sam

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Y'welcome; I'm curious if I pointed you at the right book. Is it the one that's got the circular charts showing the various permutations of Ohm's Law, and includes some wiring diagrams for flashing vs. nonflashing sidemarker lights, and so forth?

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

That sounds right to me Dan. There are a number of exercises with volts in the top half of a circle, and ohms and amps in a bottom quadrant each. He gives you many examples where one of the sections is blank, and you are asked to fill in the missing value. This book is quite interesting because it seems to be designed to teach non-college bound guys, who must still be bright guys, how to analyse a problem in the most logical maner. It seems a little pedantic at times, but he stresses always going back to basics, and not accepting any answer that violates fundamental laws or principals in any way. This sounds like someone else I know.
By the way, when I startred rewiring things I discovered that the toggle switch that was supposed to be turning on the fuel pump,(actually shutting it down) was mistakenly wired, by me, to shunt the battary voltage to the switched B+ fuse blocks. I just plugged connectors together incorrectly. This should have been OK, accept that the toggle was defective, and only worked somtimes. Couple this with the iffy ignition switch, and I wonder why it ever started. I am putting better toggles in now.

Sam

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In answer to Dan's question of why I chose fusible links over fuses for our club giveaway Fury...

I could have used a big ~120A fuse, but chose to use a fusible link instead for several reasons:

1) space - it was a in a very crowded area and I couldn't easily see how to fit a 100+A fuse holder in

2) cost - a quality fuse holder for 100+A isn't cheap

3) reliability - high current connections tend to oxidize and corrode over time (although gold plating helps a lot)

4) to encourage any well meaning fellow club member who might manage to fry a link to stop and call me, rather than pop in another fuse (or worse a bigger one) and continue on.

Keep in mind that a fusible link is just a kind of fuse; it does the same job, but is rather old-fashioned. Conventional fuses have the advantage that 1) they're easy to replace 2) shouldn't release smoke or debris and 3) are fairly precise, but the disadvanges of 4) need a holder, 5) so have extra connections to give trouble and 6) internal breakage of the conductor possible due to vibration.

In general, fuses make life simplier for troubleshooting and repair; if I thought big shorts would be a yearly occurance I'd go with fuses. I view the fusible link as the very last line of defense to prevent the car from burning to the ground and hence something you shouldn't be repairing very often. I've never ever had a fusible link itself give trouble, but I've had fuses fail internally and also fail to make good contact the their holders after a few years.

Fusible links' ratings are pretty "fuzzy"; they won't be nearly as precise as modern fuses, so if you want something with, say, <20% control or better, go a fuse. Also, if it's important to not get smoke and debris from it if it goes, definitely go with a fuse.

In summary, it's more a matter of preference that science.

I am mostly finished with the re-wiring. I left the old black B+ alt wire disconnected from the B+ bus, taped off, to be removed later when everything proves to work ok. I also disconnected the old blue, and brown ignition wires , as I now have a toggle for both the ECU, and the ACCessories fuse block under the hood, which powers the MDS box. They are taped off for removal later when I am sure everything is going to work without them hooked up.

It fired up fairly well, considering I have never tried to run it in weather this cold since I installed the Accel ECU. Fairly well means it did not act like the ignition simply was not firingn at all, as it did before this rewiring work. It was running way rich after it started, but I could not tune it for this temp because the battery on the laptop had died. So, I felt good about progress, but had to put things to bed until the laptop gets charged. Once I get the warm up curve set correctly for this temp (35 degrees), then I will have to go back and tune the start fuel for that temp. Hopefully all the wierd little quirks that had been in the mix for so long will now be gone.

Thanks for everybody's advice here. I am eager to move on from here.

Sam

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Sam
Glad we could help. When I go turbo Ill be looking to you and your wonderful posts.
Thanks
Frank

_________________
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

Great job! I imagine you'll have some retuning to do now you haven't got electrical issues masquerading as fuel problems.

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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 hope you are right about that. Does it help to keep your fingers crossed?

Do you think improving the ignition changes the apparent AF ratio? It seems to run richer now. Or is 14.8:1 always 14.8:1 regardless of how well it is fired? Maybe I should post this theoretical question on the EFI section.

Sam

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