Delco Alt light stay on?

I am in the midst of a delco alt conversion and have a couple of simple questions that I can not find simple answers for by searching (too much info):

1. the light installed in the line from ignition to terminal 1, does it stay on when running? i plan on using the existing alt light in the speedo cluster but if it stays on all the time I will just use a resistor.

2. Power sensing line to terminal 2 from harness; is there any reason why this cannot come from the coil power lead? is this what can make your engine continue to run after ignition is shut down.

trying not to have to run more wiring around the jeep when there is existing wiring in the harness that may serve my needs.

simple questions, simple answers please. I have read most of the alt conv threads out there and there is way too much info to find this.
thank you in advance for your help

 

I've done this conversion several times now. Here's what I did & how it worked for me. Mount the alternator in the best "clock" position for your application. Remove all of the old voltage regulator wires from the harness & save 'em for when you do that factory class restoration. The big heavy wire from the harness goes to the big alternator terminal just like it did before (I know that you already know this, but I didn't want to leave anything out). I make a jumper to also go on the big terminal & with a spade connector it goes to the larger spade connector on the back of the alternator (see the plastic connector from the donor car to see what I mean by larger. I use the plastic connector to help insulate the connection). The last wire left is the idiot light wire from the harness & it goes on the smaller spade connector on the back of the alternator. It's done! Here's the only issue I've had with all of my conversions............the idiot light won't go out until I rev up the engine to 2000 RPM's or so, maybe even more. After that it's fine irregardless of how slow the RPM's get. Don't know why, maybe somebody who does can tell us both. Hope this helps!

 

Thank you, that is what I was looking for. I think, by my reading everything I can find on the subject, that by using the jumper from the hot to the voltage sensing terminal (large spade) you are pretty much turning it into a self exciting alternator (1 wire). that is why you are having to rev it to turn the idiot light off. not a problem, I can live with the light if it will shut off after I rev a bit, just didn't want it on all the time because then It would be indicating an idiot and I can't have the world knowing that.

Thanks again :stout:

stand back, I'm goin in!!! :twisted:

 

MAD Electrical has a great diagram on how to wire a DELCO alternator, Their Web site is www.madelectrical.com

 

It's up and charging, JAB I wired it just like you said and it works just like you said, took about 10 minutes start to finish. this ought to be one of those topics covered in the tech section.
thanks for you help :stout: :stout:

 

Jab, Will this work on a 55 f-head converting it from 6-volt to 12-volt? Thanks tater

 

Assuming you do the 12 volt conversion properly it will work properly.

 

I was told by the alt shop to leave the lug for the cable the same, and run BOTH wires from the plug to the "hot" side of the ignition. on the smaller wire run a light to allow the alt to energize. works like a champ.

 

I don't understand what you mean, could re-explain it? With this method will the idiot light still work? It sounds like you're saying to hook up all three wires (battery & both spade connectors) to the same big lug on the back. If you do that, where does the idiot light get it's input? Or are you saying to leave the battery wire all alone on the big lug & connect both spade terminals to the hot side of the ignition switch? If this is it, again, where does the idiot light get it's input? Or is it left out of the picture leaving you to rely on an in-dash voltmeter or ammeter.

 

leave the big lug alone. the wires coming from the plug both go to the hot side of the key. the smaller one goes to the idiot light before going to the key. no other wires are needed.

 

Ok, but in the existing harness, depending on what year you have, all that is already done. Your'e basically suggesting to just hook up the big wire (I called it the battery wire, but it's really from the ammeter in my jeep) to the big terminal, which is what I do. Then you say to hook up the big wire in the plug to the hot side of the ignition, which I is what I've done by jumping it to the big terminal, & then the small wire to the idiot light, which is where it already goes in the harness. If I understand you correctly, you then add a wire from the idiot light to the hot side of the switch. I think I accomplish the same thing by installing the jumper from the big terminal to the big spade. I'll have to check. Anyway, what I did was copy what my parents had on their cars back in the late '70's when I did my first conversion. My Mom had a 250 ci. 6 cyl. Caprice & may Dad had a 305 V8 in the Chevy wagon. They both had that added wire so I just copied that. In fact, I may have used the wire that came with the alternator right from the junkyard. I'm not disagreeing with you, as obviously my method isn't perfect, as my parents never had to rev it up to get it to charge...........hmmmmmmmmmmmmm something else to play with...........

 

I've done this conversion many times. There is info out there that will say to not run the wire from the plastic connector straight to the alt lug. The reason is this wire senses voltage in the system so the alt can adjust its ouput. If you run this wire downstream, say to a positive junction block somewhere (horn relay for instance, if you are using one) it can better sense what the system load really is, rather than just measuring it at the back of the alt. If you think about it, it makes sense, otherwise why did Delco have the extra wire there, they could have designed the alt without it. I think the MAD website may have this discussion on it.

Bottom line, I extended my "sense" wire to a point further away from the alt and can't tell any difference in the way the system performs. In theory it is better. I say don't bother.

I had a Delco conversion in a Toyota that had to be reved to turn off the light. The system I currently have in my 67 -5, the light turns off as soon as the engine starts. I'm sure there is an answer why it sometimes happens, but I don't know what it is.

Glad to hear you are up and running.

 

another thought: run a wider pulley to speed up alt.

double checked my wiring, and the dash idiot light is bypassed in favor of a larger (and easier to find) turn signal bulb. the light comes on when the key is turned on and goes out when the motor starts.

 

I thought about the larger pulley thing, just might work. However on mine the pulley is a smaller one and it turns off at start up.

Another thought: my alt is a 12si, slightly larger w/higher rated output. Usually can be identified by the large plastic cooling fan vs stamped metal cooling fan. Hookup is the same. Maybe that has something to do with it?

 

When it is wired from the hot ignition to the bulb and then to the alternator it will go out when the system's output is equal to the charge in the battery. The power from the two sources meet at the light, stopping electrical flow to it.

 

er uh guys, a larger pulley will slow the alternator down won't it?

I have the 12SI and I have to rev to start it, doesn't bother me that's why i have a volt meter in the dash.

 

HAHA, Randy's right, larger pulley would slow it down. Doh...