Alternator
 

What is the part number or car/truck year and model so I can purchase a internally regulated alternator. I tried using the part number shown in the stickie but parts stores tell me it’s back ordered indefinitely.

Also, what would be the best amp to choose for stock factory harness with A/C, electric fans, and aftermarket lights and radio. Just don’t want to burn truck up with too high an amp output. There is a possibility of going to dual batterie in the future.

Re: Alternator
 

i personally upgraded to the CS 130 , very easy to do and gives you all the juice you need , ill see if i can find the thread http://67-72chevytrucks.com/vboard/s...ator+upgrading , you will find in electrical board if link not work

Re: Alternator
 

That statement is incorrect.. An alternator generates only the amperage called for by the electrical items.. For instance: Lets say you have a 100 amp alternator.. If The AC and ignition is all that's turned on and their total amperage demand is 30 amps, that's all alternator is making.. Turn on the headlights and the demand goes to ~ 40 amps.. The alternator automatically ups it's output to meet the new demand.. The thing to consider when selecting an alternator it to select one that makes more amperage "wide open" than the total amperage demand of the electrical system.. A 130 amp alternator will not "burn up" any parts of the system just because it's more than what is needed..

Re: Alternator
 

I went through a similar situation a couple years ago, got lots of great help & advice here. The one I got did the trick and I'm very pleased with it. It's a 94A alternator for an '85 Buick Riviera, O'Reilly's p/n ULT R111785A.

https://www.oreillyauto.com/detail/c...-buick-riviera

Re: Alternator
 

I currently use an ACDelco 63A 10 SI, P/N from Rock Auto, alt P/N 88864305, plug clock @ rear view 3 o'clock. $57.89 w/$25.00 core charge ($32.89).
It powers everything fine, but I have a mechanical fan and no high power draws like high wattage stereo gear.

However, I have notes in my spreadsheet that if needed I can upgrade to 85A 15 SI, ACDelco 334-2128 {#19135686, 88863357} or 78A 12 SI, ACDelco 334-2156A or 335-1094, 3 o'clock.

Re: Alternator
 

I just did this conversion, I went with a 10si. I ordered an alt for a '79 Monte Carlo with A/C.
Here's a link to that thread:http://67-72chevytrucks.com/vboard/s...d.php?t=820083
A 12si alternator wires in exactly the same.
A CS series alternator hooks up almost the same, except you have to install a resistor.
Probably way more helpful than my thread; here's a link to the Faq by VetteVet: http://67-72chevytrucks.com/vboard/s...d.php?t=815300

Re: Alternator
 

I would do a couple of things in your situation. I would get rid of the factory ammeter and go to a voltmeter. I would change to a CS144 (I would not use a CS130 as a paperweight). Delco #8077 pigtail is used if you have a lamp on the dash and the #8078 has a load resistor for use with no lamp to go from SI wiring to CS so you will have to do some adapting(different plug at alternator, but can use the same sense wires). Application for a 140A CS144 is '95 Buick Roadmaster. Then I would add a bigger wire from the alternator output to the battery. I might also add a junction block near the battery to power the fans and amp, that way you don't add any high loads to the original harness. While I was wiring, I would add headlight relays as well (to get brighter headlights and take load off the original switches and wiring).

If you don't want a CS144, then a 12si in either 78A or 94A. Anything bigger may have cooling issues. The 84-85 Corvettes do have a 12si that is 120A, but I would go CS144 if I wanted over 100A. 94A 12si is Delco 321-269 application '85 Riviera with 305Y, HD cooling and a/c. 78A 12si is Delco 321-244 application '85 Cutlass Supreme with 305Y. Nothing wrong with a 10si, I would just get a 12si if I was making the change since they have improvements. Don't use a 10si fan on a 12si, you have to get the 12si fan so be sure what you buy has the fan on it.

Re: Alternator
 

I forgot to mention the previous owner installed a Dakota Digital Dash cluster, so I do not know if there was a ammeter or light on the original guage cluster.

Also, my alternator is mounted on the Driver Side.

Re: Alternator
 

You just need to be sure to get rid of the ammeter wiring, it's probably already gone and wired as a voltmeter style with that dash.

On a 10si/12si alternator they are easy to re-clock. The alternator p/ns I gave are for 9:00 which should point the connector at the driver side.

Re: Alternator
 

Here is a link to what I did to convert to a late model alternator it may help you. Starts at post 467.

https://67-72chevytrucks.com/vboard/...698377&page=19

Re: Alternator
 

So after looking at the mounting bracket that is on the truck I am not sure a CS will fit. is the Bolt pattern / spacing the same for the SI as what I currently have installed?

Re: Alternator
 

Looks like you have a long water pump and later accessories with aftermarket upper alternator bracket? You may have to modify the upper bracket, but the bottom would bolt right in. When I did mine (in an '83, so RH side) I used mid-80s style crank and water pump pulleys that had a serpentine style for just the alternator, it has v-belts for a/c and p/s.

Re: Alternator
 

This was all on the truck when I purchased it. Does the 10SI or 12SI have the same bolt pattern as the 10DN that I currently have installed. or will they require modifications as well?

Re: Alternator
 

10si, 12si, and 10dn are all dimensionally the same as far as mounting.

Re: Alternator
 

well I had a brand new in the box 12SI that has been sitting in my garage since 2000. I was going to install it, decided to go down to local parts store and get it tested, it failed. i will be purchasing a new one this evening.

thanks everyone for all the help on this issue.

Re: Alternator
 

So I installed the 12SI and it charges fine while driving 14.7v) but at idle it’s only at 13. Is this normal?

Re: Alternator
 

Minimum should be 13.5V. Did you have any accessories running? It may well be that it is 13.5V at the battery, though. Don't condemn it, just yet. Measure it at the battery with a meter just to be sure.

Re: Alternator
 

The measurement was taken at the battery. That is why I was questioning it.

Re: Alternator
 

All Alternators drop off at lower rpm. If it's holding close to 13.0 at idle with AC and lights on, you'll be fine.

Re: Alternator
 

OK, at the battery. Were the lights and AC on?

The 13.5V is no load except the ignition- it has to be running, of course.

Re: Alternator
 

That was with nothing but the truck running. No lights ac or even radio

Re: Alternator
 

OK, if the battery stays charged I guess it's alright. I just remember from my mechanic days that 13.5V was the minimum to charge a battery on vehicles.

Re: Alternator
 

That number will change a little with ideal speed. If it is real slow. I didn't know that alternators had a use by date. LOL.

Re: Alternator
 

i do know that an alternator can loose its magnetic charge and you have to "flash the field", but that is not the case here as it does charge the battery just not charging at idle.

Re: Alternator
 

A couple of thoughts. First check your voltmeter on a different vehicle or other 12 DC source. Nothing more frustrating than searching for a problem that is in your meter. Don't ask how I know. :lol:
Check the battery voltage with the engine running, then move the positive lead to the alternator output post and compare the readings. They should be within .25 volts of each other.
If not mostly likely there is a bad connection in the wiring. To find the voltage drop place the black lead on the positive battery post and put the red lead back on the alternator post. Ideally you should read zero.
If the meter shows the missing volts from the first test the bad spot is on the positive side of the circuit.
If you get zero volts then put the black lead back on the negative post and move the red lead to a good ground on the alternator case. You should see the missing voltage.
Once you know what side of the circuit has the voltage loss you can divide that side of the circuit in two and test.
For example say the test on the negative side read .05 volts. You would then move the red lead from the alternator case to a good ground on the frame. If you're still seeing voltage then go to where the negative lead connects to the truck. If no voltage is read then check from the frame to the alternator case.
You may find it necessary to check the individual connectors on a cable to pin point the problem.
The theory behind this is a perfect wire with perfect connections will not drop voltage so the meter will read zero volts. But if there is a bad connection resistance is added to the wire and the voltage will drop. A volt test across the bad connection will show that voltage.
Good luck and keep us posted!