Another ammeter bypass question

[273valiant]

Hey guys,
Not looking to get torn a new one about using the search function, I have. My question is a simple one that needs a simple answer. I am doing the mad ammeter bypass because of some melted wires over the weekend. Pulled the black alt wire and the red ammeter wire which were melted and am setting up the new fused ones. Stayed with factory size 12gauge wire from alt to ignition relay and now has a fusible link.
Here is my question. I used a 16 gauge fusible link on the 12g alternator wire. Is that too small for the output(stock, 50amp I think) Should I cut it off and put on a 14 gauge or am I safe?
(I also used a 16gauge link on the red and black wires from the ammeter)

thank you for your wisdom

 

[67Dart273]

The problem with fuse links is there is often little or no documentation about their amp ratings similar to a fuse/ breaker. I would not fuse the red black up in the dash, you want the fuse close to the source, the alternator and the battery, and BIG on the battery. Make sure you inspect/ fix the bulkhead feedthrough stuff.

Another way around this is to get the bulkhead in good shape, connect the ammeter wires, leave the old wire in place, and run a new, larger wire from alternator to battery with a fuse/ link/ etc in that line also.

I think Crackedback came up with this, and the only issue I have is properly fusing it. You could also use the big fuses like used in the stereo world "max fuse" is one buzz word

 

[273valiant]

For sure crackedback has some great looking harnesses. I’m in Canada so it’s already hard enough to get anything from the states without it also being way more expensive. That said I was looking for a quick fix with what I have in the garage which is why the mad solution looked to be my best option, seems to have worked for a ton of members here.
I just don’t want to blow the link well I’m out cruising if I made it too small

 

[kursplat]

i'm wondering why it burnt up. loose connection, overload, new equipment wired in a bad location? so you're cutting out the ammeter, was it the ammeters fault?

 

[273valiant]

Great question, the fusible link went because I did something stupid, caught that. Well I was going in to replace it I started tracing wires and found all the damaged wires and melt damage at the bulk head from the other wires. Looks to be old as far I can tell. I also had a bounce on the ammeter needle.
Before I damaged the link I went out to get some beers and it died, long story short got it home and here we are

 

[Dana67Dart]

If you use a fuse go for a slow blow type. They can handle the surges without popping, might even look into auto or manual breakers ( used on some newer cars)

 

[273valiant]

Good tip, I actually just finished and was able to get the car started again. So seemed to fix my issue.
I used the fusible wire link for the alt wire to ign relay. So you suggest switching that to an actual in line fuse?

 

[67Dart273]

Not necessarily just see if there is documentation on the link you used so you know what amperage it is supposed to be. The size of the alternator "makes some difference" LOL

 

[RustyRatRod]

i'm wondering why it burnt up. loose connection, overload, new equipment wired in a bad location? so you're cutting out the ammeter, was it the ammeters fault?

RIGHT. That was my thought. Normally, unless you tax these old girls with lots of electronic unneeded wizardry and large by huge alternators, they work "pretty good" as is, as long as everything's clean, grounded well and in good shape.

 

[Kendog 170]

I bought 3 different size rolls of Fusible link wire and made my own. I keep spares in the glove box of both my Darts. I'm still stuck on some old school ways lol. I had a chart for sizing them using Ga. and length of wire used but can't seem to find it. So if your worried about it make some spares .

 

[Mattax]

Stayed with factory size 12gauge wire from alt to ignition relay and now has a fusible link.
Here is my question. I used a 16 gauge fusible link on the 12g alternator wire. Is that too small for the output(stock, 50amp I think) Should I cut it off and put on a 14 gauge or am I safe?
(I also used a 16gauge link on the red and black wires from the ammeter)

It depends a lot on how you wired it.
The rule of thumb is 2 wire ga. sizes smaller than the wires you want to protect.
This only works well when there is one path from the power source to the short.
Using the typical factory power scheme, only 1 fusible link was needed.
This was also true for at least one of the optional wiring schemes, the one used with rear window defrost grids around '73-'75.
Optional fleet wiring schemes had multiple fusible links. Bigger gage to protect the bigger wires, and smaller gage links to protect the smaller wires. 1976 A-bodies also used multiple fusible links

Basic concept
Fusible Links in Charging Systems with Ammeter

Stock output.
Output depends on demand. The alternator's capacity to make power is simply a limiting factor.
You can look at the dealership data books for your year and model to see what the alternator ratings were.
The 1970 Hamtramck Registry Library Page (1965 - 1969)
There was a '50 amp' alternator option in the '70s.

 

[RedFish]

Fusible link should be 2 sizes smaller than the wire it protects. I've always felt the factory 12 gauge wire was a bit small for the amount of current on it. Blower, wipers, lighting, a/c?, everything. It adds up. Replacing it with a 10 gauge wire into the cabin is not the answer. Relays to move some of the current off the 12 gauge wire is smarter. Headlight circuit is the most common application of relays.

 

[Mattax]

For reference:
This is an optional 'Fleet' type wiring for a 1973 B-body with Chrysler 60-amp alternator.

The 10 ga wires are protected with a 14 ga fusible link, and the 12 ga wires going to the key switch, headlight switch and fusebox are proctected with a 16 ga fusible link.

 

[67Dart273]

^^I believe that is actually somewhat different from how the A bodies were done^^

 

[Mattax]

^^I believe that is actually somewhat different from how the A bodies were done^^

I agree. Just used it to illustrate the wire size difference seems to be consistant in the factory examples.
The A-body optional routing diagrams I'm aware of:
* the 60 amp alternator with rear defroster grid. We've seen some examples posted here.
* and in the 67-69 assembly drawings sold by Faxon. Never seen an actual example in real life or posted here.

The other day I did see that option for A-bodies listed in the '68 Fleet Buyers book for Chrysler Canada. So maybe some business or goverment agency bought that option. Would love to see one.

On some website I came across nice Chrysler illustrations of those optional alternators, but then couldn't recall where.

 

[Dana67Dart]

On some website I came across nice Chrysler illustrations of those optional alternators, but then couldn't recall where

The collective knowledge we have all forgotten would fill volumes!

 

[Mattax]

the 67-69 assembly drawings sold by Faxon

What the heck. I was looking at these to guide the wiring mod I made to my '67.
Here was my interpretation of the assembly drawings.
To me the 1967 cable routing looked similar to the wiring diagram for '73 B-body fleet with 60 amp Chrysler alternator.

Wire 12 from the battery to the ammeter might have had a 14 ga fusible link or a 16 ga fusible link. I colorized it red with white stripe but if there was no other link, then it more likely was a blue 16 ga fusible link.
On the terminal block there is a wire connecting to the ammeter, and another presumably connecting to the alternator. Someplace there must be a connection to the main splice. Whether it was done at the ammeter, or done at the bulkhead connector (like the '73 b-body fleet Chrysler option) I don't know. If it was done at the ammeter, then the fusible link on the starter relay must have been 16 gage (blue).

In either case also notice the ignition run wire to the voltage regulator dissappears into main harness [14]. Since its not shown on the firewall, it may mean the VR was relocated to the fender.


View V shows (or I think it shows) 1968 routing "D Series"

There are two grommets shown. My interpretation is the one on the left is the grommet used to the ammeter on cars without a tach; and Cars with a tach use the left grommet for the tach wire and the right grommet for the ammeter wires.
The original fusible link was to be removed or cut? and placed into the wire from the battery to the ammeter.

This is view is somewhat confusing because the wire from the alternator to the terminal isn't shown but obviously has to go there. My guess is the alternator then connects to the main splice using the standard wire connection at the ammeter. That would be the same as was done on the later abodies with the rear window defrost grid.
Wire 2 is a fusible link.