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. |
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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
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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 |
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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. |
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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 |
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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. |
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Also, my alternator is mounted on the Driver Side. |
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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. |
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https://67-72chevytrucks.com/vboard/...698377&page=19 |
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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?
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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.
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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. |
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So I installed the 12SI and it charges fine while driving 14.7v) but at idle it’s only at 13. Is this normal?
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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.
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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.
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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. |
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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.
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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.
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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! |
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>>"flash the field"<<
An interesting term to use when you are talking about an AC Alternator. If we were talking about a DC Generator that term would make more sense. When discussing a DC Generator, someone will always mention Polarizing the Generator. In the first image below there are Iron Pole Pieces used in DC generators, The Field Windings are wrapped around these Pole Pieces. These Iron Pole Pieces retain a great deal of magnetism. The Polarity of the magnetism retained in these pole pieces is crucial to the correct operation of a DC Generator. When working on a DC Generator, it is common for the polarity of the residual magnetism to be reversed. It is then very important to correctly align the magnetic polarity of the pole pieces, with the Polarization procedure. AC Alternators do retain some residual magnetism, but the polarity is not an issue. In the second image, the ignition switch connects 12V from the battery, through the voltage regulator, directly to the field winding. Full Field magnetism is generated and current begins to flow in the Stator Windings. This ignition circuit is called a Exciter Circuit. Full Field magnetism is generated the moment the key is turned ON and also at idle. Field magnetism is reduced by the voltage regulator, as max voltage is reached. |
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>>The theory behind this is a perfect wire with perfect connections will not drop voltage so the meter will read zero volts.<<
All copper wire has resistance to electrical flow. The fatter the wire, the less resistance, the lower the voltage drop from one-end-to-the-other. Chevy relies on that voltage drop on the wire between the Alt and the Battery. That is the basis of the design of the Ammeter circuit. The greater the Alternator output, the greater the Voltage Drop on that wire, the greater the Ammeter indication. The type of Ammeter used in these trucks must have an External SHUNT. In this case the Charging wire serves doubly duty and is also the Shunt Wire for the Ammeter. Other Ammeters contain an Internal Shunt. This '67-72 Chevy Ammeter does not. |
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What would you expect the voltage drop on the Shunt wire to be on a stock system at idle with all the switchable loads turned off (i.e. wipers or headlights)? Hopefully the OP will be able get things back to normal. |
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That is good to hear. Congradulations!
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>>bumping up the idle by about 150rpm............... idling at around 850-900 rpm.<<
That's not what I would consider a solution. I wouldn't even consider 850-900 as an acceptable idle rpm. That's the rpm I would expect on the 1st or 2nd step of the High Speed idle cam mechanism. Earlier in post #16 you said you had 14.7V at cruise and 13v at idle. What is wrong with that? When you are talking about an automatic with an idle of 850-900 rpm, you probably have 150-200 rpm difference between Drive and Neutral. To me that is completely unacceptable. Having to BANG a transmission into drive, because of an incorrect idle rpm drives me crazy. |
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In post #16 you said 13V.
In post #30 you said you bumped the idle 150 up tp 850. Are you now saying your new 12SI is providing 12.3V at 700 rpm? In post #11 you provided a picture of the old 10DN alternator. What was its output voltage , at what idle rpm? Unless you have a high load at idle, it doesn't sound like the new 12SI is working properly. |
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Hello I think I will need this later.
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That seems to be a common problem with rebuilt stuff these days. I've replaced the rebuilt alternator on my truck twice, now. Both times for bad diodes.
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Since installing the new alternator, i am experiencing a pretty bad battery drain. is it possible that it is from the way it is wired?
I connected the 2 outside blue and brown wires at the regulator. I connected the 2 wires at the alternator plug what would be the brown and white wires (previous owner made them them the same color wires black) and connected both of them to the White wire on the ne 12si plug. I feel this might have been wrong. I ran a new 10ga wire to the battery from the the big red bolt on the back. I ran a new 10ga ground wire from the alternator housing to the ground on the battery. |
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