Wiring and Altenator question

[SS Shaun]

ok guys and gals i am a few parts and fluids away from getting my chevelle running. I took the altenator that came with the motor to the auto store to have them test it and it came back no good. My question for you guys is what altenator should i use? a one wire? something that i just need to hook up to the battery and go or do i need something else?


other question is does anyone have a wiring diagram for a 69 chevelle? my goal is to get the car wired so i can put the carpet in and get it ready to run

[SS Shaun]

i think i found the right wiring harness tell me what you guys think?

I spoke to a buddy of mine and he told me one wire altenators are no good.

[Hank70SS]

I wouldn't say a 1 wire is no good but there are better options. The old Chevy's used a 10DN or 12 DN external regulator alt. The voltage sensing was done at the main junction of the electrical harness near the horn relay. The voltage at the alt can be higher than at the main junction due to voltage drop across the alt output wire. A 1 wire senses voltage right at the alt.

You can use a 12SI alt which is similar in case design to the DN alts but has an internal voltage regulator and higher amp output. The mods to the wiring are pretty simple and it will maintain voltage sensing at the main junction. Or you can stick with the original type alt and external regulator, upgrade voltage regulator to a newer electronic voltage regulator, no wiring changes required. I still run the old style alt. and voltage reg but I don't have any high demand extras like audio amps, etc. so it works for me.

If you want to upgrade your alt to a newer internal regulator type, let me know. I'll show you where to get a wiring diagram of the changes you need to make.

I guess I should ask what alt do you have now? Do the 2 terminals where the wires plug in look like this || or like this --. Post a pic if you can and tell you what you have now.

[SS Shaun]

I will snap those pics for you tomorrow when i get home from work to tired tonight..lol

[Berg]

I know Ground Up and a few others make an alternator conversion adapter set. You only really need a pigtail but going to a 12SI is easy. Im put a 90amp in my car with a serpentine pulley of a mid-80's big block truck along with the water pump pulley and crank pulley. It doesn't look original but most people don't even notice it at a quick look. No bracket changes are required either so it was a very easy conversion. No spring tensioner either and the power steering pump retains the V belt. I ran a similar conversion on my old pickup using all GM parts and it was a great thing. I ran extra lights, an electric dual fan set and a decent stereo with an amplifier and never had any power issues. It made my headlights brighter with the wipers and A/C on at the same time. The kit is $20 and you don't have to cut any wires so going back to factory later on is easy. If you don't care about staying original read up on alternators at
http://madelectrical.com/
They have the whole theory on how these charging systems are wired and how to modify them if you want to upgrade anything. It is all very good information to have. I actually printed this out along with some other diagrams and I put everything in a binder for my cars. It is good reference material. I wouldn't go 1-wire if there wasn't a need for it.

[SS Shaun]

here are the pictures of the alternator hope that helps some

[Hank70SS]

Well your pics are of 2 different alternators. One looks like an older SI and the other a CS. Both are internally regulated so it looks like the required wiring mods have already been done. You can exchange the older SI for a rebuilt or go with the CS. If you use the CS you obviously have to replace the pulley. Not sure on the alignment of the pulley with the water pump pulley, may need to do some adjustments to get the proper alignment but will work. Looks like the clocking on the CS is correct, the mounting tabs. The CS will have a higher amp output so if you need it, that would be the way to go. If not then the SI is a pretty simple swap. Have the CS tested first if you want to use it, just to make sure it's good.

[SS Shaun]

thanks for the info man i am thinking about using the CS unit because i am not sure on what i am going to do with the car as far as what is going to be electric. i was thinking e fans, new radio with an amp. so i am not sure how that will handle it. i had an rx7 with an 80 amp alternator and it didn't hold up..lol i have a pig tail for the cs unit and from what i remember it only needed one wire like on my rx7 since its pretty much the same alternator. i am not there on the wiring harness yet but i wil look at it by the weekend for sure.