10/12 SI Alternator Conversion trouble
#1
10/12 SI Alternator Conversion trouble
Hello All,
Recently switched to the 10/12SI alternator variety on my 350 Rocket.
I have the diagram that Joe P provided some years ago that shows the proper wiring, I believe to have done this correctly.
Friend of mine was junking an 83' firebird so i pulled the new alternator off and am using that. Bought the proper pigtail connectors and i was off to the races.
Here is the issue. When i initially cold-start the car, the battery voltage is at 11.5 to 12.0V.
If i rev the engine to exactly 1500RPM, all of a sudden, the alternator kicks in and starts charging, and works great for the rest of my voyage.
Why do i need to rev the engine to get the alternator charging??
THANKS!
-Tony
Recently switched to the 10/12SI alternator variety on my 350 Rocket.
I have the diagram that Joe P provided some years ago that shows the proper wiring, I believe to have done this correctly.
Friend of mine was junking an 83' firebird so i pulled the new alternator off and am using that. Bought the proper pigtail connectors and i was off to the races.
Here is the issue. When i initially cold-start the car, the battery voltage is at 11.5 to 12.0V.
If i rev the engine to exactly 1500RPM, all of a sudden, the alternator kicks in and starts charging, and works great for the rest of my voyage.
Why do i need to rev the engine to get the alternator charging??
OK, the alternator is an internally regulated 10SI or 12SI. The voltage regulator on the firewall needs to be bypassed if it isn't already. I can't tell from the photos if the alternator wires actually connect to the HEI terminal or not. In any case, here's how your car SHOULD have been converted to use that alternator:
In the diagram above, the red wire from the old voltage regulator terminal 3 runs to the junction block on the horn relay. The brown wire from the old regulator terminal 4 goes to the GEN light on the dash. I would also lose the crappy spade connectors on the alternator and get a proper connector and pigtail from NAPA or other auto parts store.
In the diagram above, the red wire from the old voltage regulator terminal 3 runs to the junction block on the horn relay. The brown wire from the old regulator terminal 4 goes to the GEN light on the dash. I would also lose the crappy spade connectors on the alternator and get a proper connector and pigtail from NAPA or other auto parts store.
-Tony
Last edited by Tony72Cutlass'S'; August 22nd, 2012 at 05:05 AM.
#2
I dont really know which type of alternator it is... all i know is that i ripped it off an '83 Firebird that had a V6 two point something litre engine...
I think it's this one.
ACDELCO Part # 3342113 {#19135671} Remanufactured; 63 Amp
GENERATOR 2 DOORS; DELCO 10SI 63 AMPS; w/o A/C MAN CONT(C60)
What is the difference between 10 and 12 SI??
Also, i found "ALTERNATOR/GENERATOR RESISTOR" on Rockauto. Is that what you mean might need to be replaced? It's less than a dollar.
STANDARD MOTOR PRODUCTS Part # RU25 {#830478} Blade Terminals; Terminal Gender: Male; Direct OE Replacement; Number of Terminals: 2; Mounting Bracket: Yes
I think it's this one.
ACDELCO Part # 3342113 {#19135671} Remanufactured; 63 Amp
GENERATOR 2 DOORS; DELCO 10SI 63 AMPS; w/o A/C MAN CONT(C60)
What is the difference between 10 and 12 SI??
Also, i found "ALTERNATOR/GENERATOR RESISTOR" on Rockauto. Is that what you mean might need to be replaced? It's less than a dollar.
STANDARD MOTOR PRODUCTS Part # RU25 {#830478} Blade Terminals; Terminal Gender: Male; Direct OE Replacement; Number of Terminals: 2; Mounting Bracket: Yes
Last edited by Tony72Cutlass'S'; August 22nd, 2012 at 10:20 AM.
#3
Also, is it possible that the alternator in the firebird was Physically spinning faster than my olds? Maybe 1500 RPM in my Olds is equal to whatever the firebird was geared to idle at with its pulleys..
#4
The need to rev to 1500 may be there is a 1 wire reg in it or the alt was rebuilt with mismatched parts.
#5
The difference between a 10 and 12 SI is 2. Just kidding. They are the same basic alternator, just a slightly different design. The biggest difference electrically is the windings and rectifier. 12 SI have a better low rpm performance and some are of higher amperage.
The need to rev to 1500 may be there is a 1 wire reg in it or the alt was rebuilt with mismatched parts.
The need to rev to 1500 may be there is a 1 wire reg in it or the alt was rebuilt with mismatched parts.
The big red terminal goes to the same place that the old alternator went to.
So, looking at the above diagram, i found that the white wire (Terminal 2) really just connects to the red, which connects to the horn block.
So at the Moment, Terminal 2 is connected directly to the horn block, and so is the big + BAT Terminal.
Did i wire this wrong maybe?
#8
If you don't have the wire connected from the #1 terminal to the brown wire going to the GEN light then 1) you DIDN'T wire it the way I showed you and 2) THAT's why is isn't charging at low RPM. The SI family alternators require the signal from the idiot light (or a 35 ohm resistor) to turn on the regulator at low RPMs.
#9
If you don't have the wire connected from the #1 terminal to the brown wire going to the GEN light then 1) you DIDN'T wire it the way I showed you and 2) THAT's why is isn't charging at low RPM. The SI family alternators require the signal from the idiot light (or a 35 ohm resistor) to turn on the regulator at low RPMs.
I will cut the wires and splice them in properly this evening and report my findings.
( I was trying to avoid cutting the wires so the firewall would look as authentic as possible...)
#11
GREAT NEWS!
Cut the brown wire from the old voltage regulator and spliced it directly to the terminal on the alternator connector.
BOOM, fired up the cutlass, Alternator Automatically jumped to 13.5V, no need to rev.
Thanks for all the help. Amazing what one wire will make a difference.
Cut the brown wire from the old voltage regulator and spliced it directly to the terminal on the alternator connector.
BOOM, fired up the cutlass, Alternator Automatically jumped to 13.5V, no need to rev.
Thanks for all the help. Amazing what one wire will make a difference.
#12
Just to confirm, I wired up my 10SI the way Joe shows above and it works well. My understanding is you want the #2 sense wire far enough away from the alternator to give it a good read on the voltage in the system, so the alternator knows whether to raise or lower the votage output. I confirmed this by looking at the '75 Chassis Service Manual which shows the #2 wire being terminated at the junction block. As Joe shows, the #1 wire goes to the Gen light.
In my '66 big cars there are two wires to jump the #1 field wire to: a brown one going to the Gen light and a brown/white single strand. I used a brown wire from the alt to both, soldered it up and it seems to be working as intended.
In my '66 big cars there are two wires to jump the #1 field wire to: a brown one going to the Gen light and a brown/white single strand. I used a brown wire from the alt to both, soldered it up and it seems to be working as intended.
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