Need some help connecting to back of alternator
 

Regarding the spade connectors, left is 1 and right is 2?

Re: Need some help connecting to back of alternator
 

Here's how it use to be connected.

Re: Need some help connecting to back of alternator
 

But I got a new alternator and want to use a single connector so I just want to make sure which wires to soldier together.

Re: Need some help connecting to back of alternator
 

I just fixed mine from a previous owner's incorrect conversion. Check out the last page in my build thread where I talk about it. Basically, keyed power goes to the field or number 1 terminal. Number 2 terminal goes to battery. A quick way to see if your alternator field is working is to hold some steel to the back of the alternator. If the bump in the center is magnetized, the field is active.

Re: Need some help connecting to back of alternator
 

Post #3 is correct. Are you converting from external to internal or did you get a new harness kit

Re: Need some help connecting to back of alternator
 

Not to hijack the thread, what about the battery post on alternator? Is that not used since Number 2 goes to battery?

OP, what style alternator is that?

Re: Need some help connecting to back of alternator
 

Yes the post will take a 10 or 12ga wire into the harness going to batt and it is a 10si internally regulated

Re: Need some help connecting to back of alternator
 

Notes from my forward lamps harness with 10SI...I do not know the wire gauge for the small wires, I recall they're pretty small. Note I'm marginally colored blind, but seems to me I looked stuff up too, and sometimes harness colors can vary some. Problem is the truck has only started once, hmm;) JK


The 12 AWG red wire connects to the alternator’s BAT terminal on the alternator with a hex nut and ground washer, or a grounding flange nut. The wire’s rubber boot slides over the terminal, and snaps onto the alternator.

The alternator’s flat connector has a brown, and a red wire that are approximately 16 AWG. The brown wire connects to the alternator’s #1 terminal, and red wire connects to the #2 terminal. The brown wire’s circuit is a brown and white wire at the ignition switch.

A plastic coated clip retains the alternator wires, secured by the alternator’s ground terminal nut. grateful for my 72 donor, it had a vintage wire clip to fit right. The 71 clip doesn't work with a Delco 10SI.

Re: Need some help connecting to back of alternator
 

Not convertering since it's already been done to an internal regulator before. The alternator just finally went bad. Anyway, the 1st and 2nd post is my old alternator and the 2 wires from the truck, blue and white, are separate so I bought an adapter that has a red and white wire so it'll just be a single connector after I soldier the wires together. Because the spade connectors on the new alternator are mounted -- -- instead of I I like the old alternator, just wanted to make sure that the new alternator connectors are the same just mounted differently. So it seems like soldering will be white to white and blue to red.
Dang, hope that made sense.

Re: Need some help connecting to back of alternator
 

I used that same pigtail when I fixed mine. I don't remember which color wire was which, but if you run keyed power to terminal 1, or field, and then run battery power to terminal 2, you should be fine. I actually crimped the terminal 2 lead out of that pigtail into the new eyelet that I attached to the bat stud on the back of that alternator just to make the wiring neater.

Looking at your picture, is your alternator mounted on the passenger's side of the motor?

Re: Need some help connecting to back of alternator
 

Here are some great references for alternator upgrades/wiring. I used both when I switched to an internally regulated alternator:

http://www.madelectrical.com/electrical-tech.shtml

Start at post #2:

https://67-72chevytrucks.com/vboard/...d.php?t=342596

Vettevet is a great resource

Re: Need some help connecting to back of alternator
 

Good info. Yes, passenger side mounted.

Re: Need some help connecting to back of alternator
 

I hope it helps.

The person who did my "conversion" mounted mine on the passenger's side as well. I don't see that as often with the 67-72 trucks. Seems like people prefer to modify the existing mounting brackets on the driver's side. I actually like mine on the passenger's side because I don't have air conditioning and I don't have to run a heavier gauge charging wire all the way across the engine bay.

Re: Need some help connecting to back of alternator
 

https://67-72chevytrucks.com/vboard/...1&d=1767455717

Although this looks like a 10SI alternator with an internal voltage regulator it is not. It's a 1972 only external regulated 10DN.

Where the internal voltage regulator goes in a 10SI there's just a dummy block with a 10DN connector. The terminals are positioned like this ( l l ) instead of like this ( _ _ ). This "transition alternator" uses the same housing, rectifier bridge, and diode trio as the 10SI but also requires the use of the 10DN external voltage regulator.

Re: Need some help connecting to back of alternator
 

If you want to use your new 10SI alternator remove the plug from the old voltage regulator. Make two jumper wires and connect the blue wire to the brown wire and the red wire to the white wire.

https://www.567chevyclub.com/images/...ng-convers.jpg

https://www.567chevyclub.com/images/...nator-1972.jpg

https://www.567chevyclub.com/images/...nator-1973.jpg

Re: Need some help connecting to back of alternator
 

Man that's super info. above... I know Vette has a nice write-up too, always does. I didn't have to "guess" personally, new harness for the SI. Real happy with the Delco 10SI.

Speak of Chevy, watched this Youtube last night, it doesn't declare a GM. More recent stuff, 2000ish forward. Ive heard gm engines can go 300K, 2000ish forward?

Can vouch for Tundra 5.7 - with covid-flation and stuff. It's the first driver I've bought worth a lot more than my cost, when covid hit, though was a good deal even then. $ doesn't matter though, it's the last driver-truck I'll ever have. Only downside is a BA Crew cab, for only a 5.5 bed. Can't even sleep in it, but all seats recline as needed in a pinch......... Dynamite drive, super comfortable....Factory duel exhaust, even with the cap and BA chassis rivals my BBC Chevy short with HEI & 67 HP heads, 1/4 mile or such - maybe better, it seems real close, to 60-70 anyway - ish. Correct wheels trim level Rock Warrior. 2013, had 70K, now 83K. Apparently I really like it☺

I bought a new 2005 Tundra beforehand, this is the replacement. It was in great shape, no problems for 90K miles when I sold it. 15 years cost me 18K, I call that a win. I thought my "firm" price out, including the 1500 cost for maintenance to be paid by the new owner. Problem was I caught five ready to buy on the first day:lol: So realistically, it shouldn't have cost me more than 1K a year to own.

Don't care what the weight limits are on those old Tundra, pre-5.7, they're rated too high, the chassis isn't much for light duty....I towed a lot with that 2005, well within "limits" and trailer brakes, the brakes on the truck said all I needed to know, it ran through them - weight limits favored "the big three" for sure.....The 5.7 is closer to a 3/4 ton.


https://www.youtube.com/watch?v=h18GNfFNdoQ