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69 Alternator wire

Mach1 Driver

Active Member
Hey Mid, I've got a 69 Mach and I'm going to go to a 95A 3G alternator from PA Performance, who suggest adding a 4 ga. wire with a 150A fuse link in parallel with the existing alternator wire. That would be black wire #38. When I protested that if the 150A link blew it would turn wire 38 into a fuse, they said if a fuse link does not exist, then add one. I know that my 69 doesn't have fuse links, and remember you saying that Ford didn't start using fuse links until 70, and I don't know if they put one there- but I'm sure you do. If they didn't put one in the circuit do you know the wire gauge for #38? Thanks
 

Midlife

Well-Known Member
Staff member
Moderator
Ummm...I think they meant it to go inline, not parallel. Having a parallel circuit makes no sense to me. But...I'm no expert on wiring the 3G alternators, so I cannot help you there. Fusible link wires are marked by its gauge and is somewhat length dependent. For 70-73's, Ford used a 14 gauge fusible link wire (greenish yellow color) for what was essentially a 12 gauge main feed line.
 

Mach1 Driver

Active Member
I went on line and downloaded a 1970 wire diagram (mine is a 1969). They are similar but there are changes in the charging circuit, and the 1970 diagram does not show any fuse links. Since you indicated the fuse link was attached to the starter solenoid post and the only thing on the 70 diagram that is shown on the post is the battery cable and a single black wire, I assume that the fuse link is connected between the black wire and the post. If so then the fuse link would isolate the car from the battery but not from the alternator. To me that seems like only a half-way effort, but at this point I'm only trying to verify what was actually done in 1970.
 

Attachments

Midlife

Well-Known Member
Staff member
Moderator
Yup, the fusible link does not protect the car's wiring, only the battery. I don't know the reason Ford decided to do this, but there it is.
 

Mach1 Driver

Active Member
I found a fuse link made by picowiring.com on page 23. Its number 5554PT, 14ga, 5/16 terminal, 10-1/2" long, Green, for Ford starter solenoid. Were these wrapped up inside the harness or kept on the outside?
 

Midlife

Well-Known Member
Staff member
Moderator
That gets spliced into the main power lead that goes to the battery starter side of the starter solenoid. That's the piece I typically use when I can't find a salvageable piece from another harness.
 
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Mach1 Driver

Active Member
That gets spliced into the main power lead that goes to the starter side of the starter solenoid.
1. Did you miss speak or is something going on that I'm not aware of? On my car the starter solenoid is on the passenger apron. The battery cable and wire 38 Black connect to the big lug on the battery side of the solenoid. Only the starter cable attaches to the starter side big lug.
2. If that is the correct fuse link to attach to wire 38 black, is it wrapped up in the harness or is it kept outside the tape (so it doesn't melt into other wires if it blows)?
 

Horseplay

I Don't Care. Do you?
They suggest running the #4 in parallel because the stock wire size simply cannot handle the current output for those who do not want to cut up the stock harness. Ideally, they expect you would disconnect the original wire though to eliminate that hazard. Just about every install with a high output alternator uses a fuse in line. Typically in the 200 amp range. I know I wouldn't use a fusible link myself in something with that much current but I take it you are trying to do something covert and maintain original appearances.
 

Midlife

Well-Known Member
Staff member
Moderator
Yes, I mis-spoke: the battery side.
Once one goes away from stock configuration, all bets are off on wire sizes, fusible link sizes, etc. One of the hazards of customization. The 14 gauge fusible link assumes stock Ford wiring and utilization.
 

Mach1 Driver

Active Member
The 14 gauge fusible link assumes stock Ford wiring and utilization.
Yes of course. So...on a stock 1970 harness, is the 14 ga fuse link wrapped up with tape inside the harness or is external to the harness so if it melts it doesn't harm other wires? I'm just wondering how Ford made the harness.
 

Mach1 Driver

Active Member
They suggest running the #4 in parallel because the stock wire size simply cannot handle the current output for those who do not want to cut up the stock harness. Ideally, they expect you would disconnect the original wire though to eliminate that hazard. Just about every install with a high output alternator uses a fuse in line. Typically in the 200 amp range. I know I wouldn't use a fusible link myself in something with that much current but I take it you are trying to do something covert and maintain original appearances.
Yes, I've been working with PA Performance on their 3G system and it is similar to what you describe- 4ga with a 150A fuse link. I protested to them that running them in parallel did not make sense and that everything older than 1970 did not have fuse links. They said to add one, and thats how I got interested in what Ford did in 1970. Mid seems to be the only one with this information because the wire diagram I found for a 70 does not show any fuse links. I'll post a thread in the How To section here pretty quick to show what to do in a 69 or 70. PA's instructions are woefully inadequate, and would melt your main harness if the 150A fuse link blew. Its easily corrected though, and something you should consider if you ran them in parallel.
 

Midlife

Well-Known Member
Staff member
Moderator
Yes of course. So...on a stock 1970 harness, is the 14 ga fuse link wrapped up with tape inside the harness or is external to the harness so if it melts it doesn't harm other wires? I'm just wondering how Ford made the harness.
It is at the far end of the harness, and is partially wrapped around the OEM splice and back towards the firewall end of the harness and unwrapped for most of its length.
 
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