Lights dimming at idle.

[fixit-p]

Originally Posted by red71cheyenne

It looks exactly like the 100amp one wire I had on my 71 that did the same thing until I upgraded to CS130.

Those 1 wire alts are all DELCO clones the housings don't change just the regulators, haven't see one yet that wasn't a clone. the important thing here to properly identify what type of alt it is, is if the white and blue wires are connected and where (back of alt = external reg. or side of alt = internal reg.) or does the terminals look like this l l or this - - .

[john8746]

Try A BETTER Ground Engine to frame frame to cab rad support to frame good grounds work wonders

[Zeke's Garage]

Have you checked battery voltage while it's idling with the lights on? Then while the engine is at a high idle (~1200-1500 rpm)?

You want to make sure that the voltage regulator isn't putting out less than 12v at idle and slowly killing your battery.

Another culprit is old oxidized wiring for the headlights. A lot of folks are installing relays for the lights and running the hot directly from the battery instead of running through the switch. This results in much brighter lights and less heat in the wiring harness.

Short answer to all this is that you probably need to upgrade your alternator, and verify whether you are still using the external regulator. The upgrade to an internally regulated Alt is much easier than you think, and you can use cheaper replacement parts.

Good luck!

Shawn

[red71cheyenne]

Originally Posted by fixit-p

Those 1 wire alts are all DELCO clones the housings don't change just the regulators, haven't see one yet that wasn't a clone. the important thing here to properly identify what type of alt it is, is if the white and blue wires are connected and where (back of alt = external reg. or side of alt = internal reg.) or does the terminals look like this l l or this - - .

Right, I was just trying to say its not the stock alternator in there, so figuring out what it is and how its connected is going to be key to fixing it.

[Allensracing]

Originally Posted by red71cheyenne

Right, I was just trying to say its not the stock alternator in there, so figuring out what it is and how its connected is going to be key to fixing it.

right, he needs to determine if it is a stock alternator with an external regulator, a stock alternator with an internal regulator, or a one-wire alternator.

[tdp67]

Ok, I looked at it again. It has 4 wires from it, black, red, blue and white. They all are bundled through a sleeve and are all 4 plugged in to the side of the voltage reg under the driver side head light. Couldn't really see and numbers on the v reg.

[fixit-p]

Originally Posted by tdp67

Ok, I looked at it again. It has 4 wires from it, black, red, blue and white. They all are bundled through a sleeve and are all 4 plugged in to the side of the voltage reg under the driver side head light. Couldn't really see and numbers on the v reg.

Thats a 10DN externally regulated alternator and the problem your having is very common with them, I would recommend upgrading to an internally regulated alt either a 12SI or CS130.

[Allensracing]

Originally Posted by fixit-p

Thats a 10DN externally regulated alternator and the problem your having is very common with them, I would recommend upgrading to an internally regulated alt either a 12SI or CS130.

I second the motion to upgrade. what you are experiencing is exactly how the system worked (Or didnt work?) directly from the factory as a brand new truck.
there is a couple minor modifications to your wiring harness to convert to a newer style alternator. you can switch to a one wire alternator easier, but sometimes they also do not charge well at idle.

[tdp67]

Thanks for all the help y'all! Looks like I'll be upgrading to a CS130.

[mr48chev]

Originally Posted by Allensracing

looks to me like someone polished the original alternator. it looks like the shape of the external regulator style.

That is what it looks like to me too.

It won't make any difference between six or 8 cylinders but if you have added accessories to the truck the alternator may not be able to keep up with the power demand at an idle.

A bit of explanation. Most of these trucks didn't have many accessories to draw a lot of electricity and they ran the regular headlights that didn't draw as much power as the halogen lights we run most of the time now. Start the truck, put the charge back in the battery, keep up with the am radio and headlights and off down the road with maybe the wipers going or the heater fan blowing. Now days we have Halogen lights, a big stereo with an amp behind or under the seat and a full set of speakers and maybe AC to go along with that and the little 35 amp alternator can't keep up with the demand some times.

If the lights just go dim at low speeds and then everything is ok and the truck always starts I wouldn't get too excited but if you start having starting problems because the load is more than the output of the alternator and the battery is being drained when you run down the road rather than being charged it may be time for a bigger alternator.

[tdp67]

I guess my next question is, where is the best place to buy one of these at a good price?

[VetteVet]

Read this first---http://67-72chevytrucks.com/vboard/showthread.php?t=119379

[tdp67]

Originally Posted by VetteVet

Read this first---http://67-72chevytrucks.com/vboard/showthread.php?t=119379

Thanks, but I would like to stay as stock as possible. I want the chromed version too. Who has the best price on these?

[fixit-p]

If you want to stay stock you'll most likely have the same issue and your alt is probably as good as a replacement>>> http://www.summitracing.com/parts/SUM-812102/?rtype=10 a good upgrade close to stock would be this one >> http://www.summitracing.com/parts/TFF-7127NC/?rtype=7 You could do the wiring a little different to keep it stock in appearance but then again your engine is anything but stock.

[tdp67]

Originally Posted by fixit-p

If you want to stay stock you'll most likely have the same issue and your alt is probably as good as a replacement>>> http://www.summitracing.com/parts/SUM-812102/?rtype=10 a good upgrade close to stock would be this one >> http://www.summitracing.com/parts/TFF-7127NC/?rtype=7 You could do the wiring a little different to keep it stock in appearance but then again your engine is anything but stock.

Yeah, you're right about that. I guess what I meant was, I don't want it to look out of place like it don't belong.

[Allensracing]

you do realize "as stock as possible" contradicts "I want the chromed version"?
all the stock stuff looked like crap

[tdp67]

Originally Posted by Allensracing

you do realize "as stock as possible" contradicts "I want the chromed version"?
all the stock stuff looked like crap

Yeah I know! I just want it to look cool and fits with the rest of it. Is that better?

[tdp67]

Originally Posted by fixit-p

If you want to stay stock you'll most likely have the same issue and your alt is probably as good as a replacement>>> http://www.summitracing.com/parts/SUM-812102/?rtype=10 a good upgrade close to stock would be this one >> http://www.summitracing.com/parts/TFF-7127NC/?rtype=7 You could do the wiring a little different to keep it stock in appearance but then again your engine is anything but stock.

I think it's a factory crate 350. I don't have ac or stereo yet, but I plan to. How do I know which one to get?

[Allensracing]

Originally Posted by tdp67

Yeah I know! I just want it to look cool and fits with the rest of it. Is that better?

yes, I am just messing around.
your engine looks really good.

[tdp67]

Originally Posted by Allensracing

yes, I am just messing around.
your engine looks really good.

Thanks! One of the main reasons I bought it.

[tdp67]

So, I think it's a factory crate 350. I don't have ac or stereo yet, but I plan to. How do I know which one to get, and how do I convert to no outside regulator?

[fixit-p]

Originally Posted by tdp67

I think it's a factory crate 350. I don't have ac or stereo yet, but I plan to. How do I know which one to get?

I recommend this one http://www.summitracing.com/parts/TFF-7127NC/ its chrome, close to stock and is a three wire, stay away from 1 wires.

[fixit-p]

The wiring is simple in this diagram you'll see the original wiring.


The second diagram the regulator has been removed and the blue and red wires are jumped together and the brown and white wires are also jumped. The important part is that the brown/white wire goes to the #1 terminal on the alt and the red/blue wire goes to #2 terminal the ground wire is not needed anymore.


you'll also need a new connector for the alt.

[tdp67]

you'll also need a new connector for the alt.

Thanks, is there a part number for the plug? Do I get it at Painless?

[fixit-p]

yeah its a painless http://www.summitracing.com/parts/PRF-30706/ your local auto parts store should also have them in the help section.