72 Jimmy Electrical Upgrades - 1 wire alt and HEI

[chalet2506]

Bear in mind that your dealing with an electrical noob here.

I'm upgrading to a Powermaster 100 amp, internally regulated 1 wire alternator and HEI Ignition on my stock 72 Jimmy. I've got 4 wires coming off the old alternator. A ground to the body, a two wire plug that all goes to the voltage regulator? bolted on the engine compartment right behind the drivers side headlights. The hot off the alternator is spliced into 3 wires - one across the radiator to the battery, one to the the voltage regulator, and one back to the fuse block one the firewall. Also out of the splice is a black/white wire going back to the fuse block as well. Off the voltage regulator is a 4th brown wire that runs back up to the fuse block too. I'm guessing that's the wire that runs my voltmeter in the dash.

I'm running a 6 guage charge wire direct from the alternator to the battery and am going to pull out the old alternator harness and external regulator and eliminate the hot offthe splice to it.

Question 1 - My instructions for the new alternator say nothing about a ground, but its got a bolt hole in the back of the case doing nothing. Do you think I ought to run a ground to the frame off of it?

Question 2 - Why is there 2 wires coming out of the hot splice both running back to the same fuse block?

Question 3 - How can I jump the voltmeter wires so that my guage still works?

Edit - Question 4 - I would think the hot off the original, stock alternator would run through the externatal regulator, then a hot out of there would charge the battery and run your system. What's the deal with that?

Even thought the HEI seems pretty simple, I'm sure I'll have some questions regarding that down the road.

Thanks in advance.

 

[mike in mo]

ok ill start at the back with the HEI its is just a drop in part but you need to change out the hot wire the one running to the old coil is a resister wire and will not give out the full 12volts to the HEI. as far as the alt thing i dont know i have done the change over like your talking about but never did it with a kit.

 

[4X4HIGH]

You need to change the Hot wire for the distributor for two reasons, one it MIGHT be a resistor wire (drops voltage to the coil) and also it needs to be a 10 gauge wire instead of the very small wire that it currently is. Basically you're going to remvoe your olds points distributor, and the coil and replace the distributor with the cap in coil HEI and change out the wire that is currently going to the + on your existing coil for the 10 gauge wire and plug it into the BATT terminal of your HEI. You should have a (yellow IIRC) wire that goes from the + coil terminal down to the (R) terminal of the starter solenoid and this wire can be eliminated as well. The function of this wire was to proved 12 volts to the distrbutor ONLY when the starter is cranking.

 

[bp71k5]

I don't like the 1 wire alternators, but you can get a small kit to use the later model 2 wire alternators that are internally regulated. It's a super easy conversion.

#2, The red spliced wires powers the ignition, and all the electrical items in the dash as well as the lights.

#3, I don't know how to keep the AMP gauge wired, but I think you'de have to splice it between the charge wire and the battery. A more useful guage is a voltage gauge which you can run any +12V hot wire to the guage to let the guage work as long as it's a "volt" gauge and not the stock "AMP" gauge.

#4, you throw away the old regulator. It won't work anymore.

Edit: 4x4High's probably right. My 71 had a small red resistor wire and I'd guess the 72's did as well. Although my HEI was working with the stock wire somehow.

 

[chalet2506]

Thanks for the input on the HEI fellas, I've read a bunch of old threads on that and it looks pretty straitforward, I'm just going to get somebody over here who knows a little about timing - I've never messed with that.

#2, The red spliced wires powers the ignition, and all the electrical items in the dash as well as the lights.

Why is there 2 wires spliced, going to the same place? It doesn't make sense to me because you've got a 14 guage(I think) power spliced into 3 same sized 14 guage wires. It seems like the power wire off the alternator or the one from the battery would be heavier to carry the load before its split. If its just spliced so that there is two different powers to the fuse panel, why didn't they splice it closer to the panel instead of way up by the voltage regulator? Part of the reason I'm eliminating and replacing some of the old wiring is that all those wires(some are old and the insulation is cracking) and the alternator were actually getting hot - going to burn my truck up kind of hot.

There may not be an answer, since I've got it apart I'm just trying to understand why its like that. Hopefully the new wire, the new alternator, eliminating the external regulator will cure that. My ground looks good, if that doesn't I guess I've got a short somewhere else.

#3, I don't know how to keep the AMP gauge wired, but I think you'de have to splice it between the charge wire and the battery. A more useful guage is a voltage gauge which you can run any +12V hot wire to the guage to let the guage work as long as it's a "volt" gauge and not the stock "AMP" gauge.

Thanks, I didn't know this. I figured it was a volt guage. Guess I'll be looking to upgrade my dash bezel know since I also want to add a tach.

#4, you throw away the old regulator. It won't work anymore.

I was more curious as to way the current was regulated. It seems your current would originate in the alternator, be routed throught the regualtor where it was "regulated", however it does that, then the regulated current would supply the battery and your electrical system. Again, even though its going, I'm just trying to understand how it works since I've got it apart.


Edit: 4x4High's probably right. My 71 had a small red resistor wire and I'd guess the 72's did as well. Although my HEI was working with the stock wire somehow.[/quote]

Thanks again, I'll be gone hunting for a few days but will get back to work on it Monday or so.

 

[bp71k5]

Why is there 2 wires spliced, going to the same place?

Are you sure they go to the same place? It's possible mine or yours was altered by a previous owner. Do they both terminate at the same terminal on the fuse block?

 

[chalet2506]

You're correct, they end at two separate terminals on the fuse block. I guess I'm done kicking that dead horse.

After digging around on CK5 it looks like the burnt up red wire coming off the junction box on the fire wire wall that is wired to the positive terminal of the battery is a fusible link(that's a new one to me). Also, there's a little plug with a fuse on the black wire that comes off the same junction block.

Any idea what amp those are? The fuse in the plug came apart and what's left is stuck in the ends. I'm thinking of getting rid of both and adding either a couple of large fuses or circuit breakers to the fire wall next to the junction block instead.



Also, I'm thinking the reason for the meltdown has to do with one of two things. A loose battery terminal on the positive side - since I had a battery drain I was just keeping it hand tight so I could get it on and off quick. Or the fact that the bottom bolt holding the alternator to the bracket didn't quite fit, so I beat it through with a hammer(do you think Napa will warranty that?.) Basically I was trying to cram too much work into too little time here a the office and ran out of both time and patience. Flame away.

So new circuit protectors, new wire off junction block to splice to fuse panel and new alternator ought to fix things. I just need to know what amp the fuses or circuit breakers need to be.

 

[bp71k5]

You're correct, they end at two separate terminals on the fuse block.

Do you have a factory wiring diagram? I've got one here and it really helped me out when I was doing this stuff. Mine did not have two big red wires going into the fuseblock. I did add a big red one to power some additional stuff in the dash so that could have been what happened to yours.

Also, there's a little plug with a fuse on the black wire that comes off the same junction block.

Mine says it's 4A. There also used to be one on the drivers side in about the same place and it hooked up to the headlight switch (I think). I did the headlight relay update so lots of my wires are not stock anymore.

 

[chalet2506]

I've got a Haynes manual with a wiring diagram. According to it, there's a 16 guage wire with fusible link between the battery and junction box, and then the two wires off the junction box to the fuse block have inline fuses. So it looks like mine has been changed or came from the factory a little differently. I read a little about fusible links but couldn't find any way to figure out the amperage. According to the manual, they're 4 guage lighter than the wire they're protecting, but that's all it would say.

I was over at Napa getting some other things, so I picked up some new 14 guage wire and a couple of 30 amp breakers for the new supplies to the fuse block. Also got 10 feet of 6 guage battery wire and ends for the new alternator - battery cable, and 10 guage wire for the HEI.


Edit - Also, I was reading through your thread on the conversion you did to electrical gauges. I'd like to do the same thing to mine. I think I figured out the volt and water temp guages you used, but which tach would be the press in fit?

 

[bp71k5]

fusible links are just wire that is a smaller guage than the wire it protects. It melts before the main wire melts. So if you want to protect a 12g wire, use a 16g fusible link. They sell lengths of it at the parts stores, and sometimes sell individual sections of it with ends already crimped on.

My book lists fusible links between the battery and the junction block. The wire between the battery and the block is the fusible link itself.