Successful 3G Alternator conversion - my notes and a few q's

I couldn't add to this older thread:

While I'm not a super experienced mechanic, I share my experience in hopes of helping someone else. My Bronco is a 1970, with I believe an October 69 build date.

Before you get started:

Make sure you have a fire extinguisher handy, and an escape path.
Be safe, take your time. This is pretty easy to perform, but you do have to think things through.

Background - after almost 20 years parked, I decided it was time to get my truck running again. Found out that either my 1G, its wiring or the voltage regulator were junk. Knowing I'd need more output later, I decided to tackle the 3G retrofit. Honestly, the install was pretty straight forward, but I did run into a couple of things which I share below.

The alternator was a pull-a-part unit I 've had for a couple of years. Don't remember what it was pulled from, but I did pull a good portion of the wiring harness that goes to the to the "ASI" three connector plug. This was good - I had plenty of the light green with red stripe wire to work with, and saved me from having to buy a connector.

I did do something remarkably smart before I got started - I took the alternator to a parts store to test its operation. There was no cost for the test, and I was assured things were going to work if I did my part correctly.

On my 3G: the bottom ear / tab on my 3G was not threaded, so I picked up a 2 1/2" bolt, lock washer, and some washers for the install. the long top bolt and its spacer were reused and fit perfectly. I must have "clocked" the back case on the alternator when I first received it - the connectors were pointing up in the 10 o'clockish positon and ready to go.

I did splurge on a positive cable and fuse kit came from Wild Horses - Part #6025. I had 90% of the junkyard parts but figured this was worth it to have new copper and a decent fuse mount. Speaking of the fuse holder - big thanks to Jeff10 for sharing how he mounted his here - that was super helpful

* I used the BC Broncos wiring diagram - 4th link from the top of the list.. The light green with red stripe ("I" wire from the alternator wiring is connected to the "S" connector from the stock 4 position voltage regulator plug. On my truck's harness it was a regular green (darker) with a red stripe - almost identical.

So I pull all the old stuff out, install the "new" stuff, and go to crank the truck - completely dead, no power to dash / headlights / turn signals. Long story short - during removal of the cabling from the "battery" side of the solenoid (faces the front of the truck), I should have replaced one power cable. It has aring connector that runs to 6-8" of black wire, then has a "splice" block that splits this to separate yellow and black wires. (This is the one "oddball" photo with the wire pulled out of the loom.)

I have dual groove crank and water pump belts due to my power steering conversion. Was going to run a dual groove pulley on the alternator, but didn't want to hassle with it right now as my truck is 95% stock electrically. So I decided to run a single groove, larger diameter pulley, this one specifically: "NEW Single Groove Delco Alternator Deep V Belt Pulley Chevy Chevelle Camaro Nova". Charging seems fine for now - at idle, I'm putting out about 13.7 volts. Later on I'll either go dual (smaller diameter pulley will provide more output at idle) or - better yet - do a serpentine conversion.

All connectors were heat shrunk after crimping, in an effort to keep moisture out of the connector. There were a couple of nicks in my junkyard harness, that's why you might see shrink tube in odd spots.

I still have some wiring removal / clean up to do. The 4 position regulator conector was removed (saved connector, took female ends out). Anything left is either covered with shrink tubing and / or silicone tape. Not sure how I'm going to dress / secure my wire, so for now I'm just using some decent quality loom from wire barn for protection. Suggestions you have (and photos) would be very much appreciated.

Also needed is a voltmeter... But given my ammeter wasn't working I do feel better about the charging situation overall. I shoud also mention I have yet to remove any of the ammeter wiring.

If you made it this far - I hope you found this helpful, and thank you for reading.

I did have two questions for the gurus:

* Should the radio noise suppressor be reinstalled or upgraded? Eventually I am going to put a stereo and amp back in, so mabye something better for that circuit.

• I'm running an Edelbrock 1406. PO had positive lead to electric choke running to the coil, which I know is not correct. Where should this run to?

the choke I hooked up to key on hot connection which for me was the green wire with red stripe. my old ford carb had the idle solnoid when removed left me with an open pig tail connector.

Rustytruck said:

the choke I hooked up to key on hot connection which for me was the green wire with red stripe. my old ford carb had the idle solnoid when removed left me with an open pig tail connector.

Click to expand...

Thank you for the hint. Ended up wiring it up like that.

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For all your work, I hate to see those battery cable clamp ends.

I'll be referring to this when I upgrade my alternator. I bought a higher amp internal kit from JC Whitney 30 years ago for mine and it has served me well but I'm always concerned it either isn't putting out what it claimed or it is short lived.

I wouldn't worry about that pulley any time soon. What makes it work is the groove depth that grabs the entire side of the belt. The effective diameter is almost the same as a stock pulley so any improvement in idle output will be minimal. I've been running mine for 7+ years with no issues. As 94OR mentioned, i would find some different cable ends asap.

.94 OR said:

For all your work, I hate to see those battery cable clamp ends.

I'll be referring to this when I upgrade my alternator. I bought a higher amp internal kit from JC Whitney 30 years ago for mine and it has served me well but I'm always concerned it either isn't putting out what it claimed or it is short lived.

Click to expand...

Agreed, my battery (and starter) cables have seen better days. Patched together to get me by for now, I'll replace soon.

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Slednut10 said:

I wouldn't worry about that pulley any time soon. What makes it work is the groove depth that grabs the entire side of the belt. The effective diameter is almost the same as a stock pulley so any improvement in idle output will be minimal. I've been running mine for 7+ years with no issues. As 94OR mentioned, i would find some different cable ends asap.

Click to expand...

That makes sense about the pulley.

And I'll replace the cables soon.



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Can't go wrong with these, been serving me well for a long time.

https://www.wildhorses4x4.com/product/Custom_Battery_Cables_Set/Bronco_Batteries