SBC 10SI good but no output??????

[jkl72-40]

71 fj55 sbc
I have a 10si that is good (had tested) but is not charging the system. I have been runing this set up for 4 months and now its not charging and I cant find out why I cant find anything wrong with the wires but obviously there is a problem. how do I check the exciter wire? batteries are holding a charge. I have good grounds even an extra one. any help??

 

[inkpot]

Howdy! Does the alternator have an internal regulator? Are you still using the OEM regulator also? John

 

[jkl72-40]

gm 10si ....internal

 

[inkpot]

gm 10si ....internal

Yea, I thought all of that style is internal. So did you wire past/remove the regulator on the fenderwell? You can't use both. John

 

[jkl72-40]

removed it..... this is what I am reading How to install a GM Alternator in a Land Cruiser...

another question if I run the 10si will it burn my ammeter? this is what I read:
Ammeter should be disconnected if you are using anything more powerful than the stock alternator. All of the charging current travels through the ammeter, so a 80+ amp chevy alternator charging at full output will kill the 10 ga white wire in the wiring harness. Not good.

but my light still comes on when the key is turned on but the motor is not running any ideas??

 

[inkpot]

My alternator is 80 amps, and I overdrive it by running a larger crank pulley. That make the "excite" issue non existant. I have run this for 16 yeas with no problem. I will read back thru that link later. I don't remember it very well. John

 

[bsmith123]

alt issues

"a 80+ amp chevy alternator charging at full output will kill the 10 ga white wire in the wiring harness. Not good."

If it did it would "kill it" by melting it due to too much current flow through it and that should be obvious---it could kill the ammeter however and that could cause a prob with getting power to the circuits easy enough to check input/output of the ammeter---is it even reading? What year is your rig? --probably could tell you where to test/how to bypass it with a look at the schematic

how do I check the exciter wire? batteries are holding a charge
The exciter wire should have 12 volts with the ign key in run

"My alternator is 80 amps, and I overdrive it by running a larger crank pulley. That make the "excite" issue non existant."
Actually a larger pulley would make it run slower not faster


Exactly what are the symptoms from what I am reading you say the batts are holding a charge, you have lights, but the motor wont run?

Is it turning over? If your alt was bad you'd expect the batt to be dead, if not this sounds like an ignition or start circuit issue

a bad alternator should not keep the car from starting with a charged battery installed

Tell us what you have as far as symptoms

 

[jimd4x4]

Kyle that link you have is correct. As long as you are sure it is internally regulated. Look at the connector on the altenator. There are two spade terminals and the differnce is.

[ ] External Regulator
_ _ Internal Regulator

I used a 1 wire altenator with my SBC conversion. You should be able to get most anywhere. Than just 1 heavy wire from altenator to battery.

 

[inkpot]

"

"
Actually a larger pulley would make it run slower not faster

Howdy! A bigger crank pulley makes the alternator go faster. A bigger alternator pulley makes alternator go slower. Think about a 10 speed bicycle. John

 

[cruiserjunkie]

make your own one wire setup so it self excites. I use 140 alt and run it through the gauge but with after market harness and have yet to hurt gauge

 

[jkl72-40]

its a 65 amp 10si internal stock wire harness
the system/lights drains the battery, I can charge it with a charger and they will hold...
the motor will start/run
no melted wires
71 fj55
alt tests good but not charging the batteries
I am going to try the 1 wire setup for now but I read there are draw backs to it. cant recall what they are tho

I will post what i will do

 

[jkl72-40]

alt

will runiing a wire from the #2 lug to the battery lug then to the battery work? I would not have a gauge tho....
will this work

it was like this:

*black with white = stater soleniod(if you cant tell the stripe color anymore, check with a voltmeter or easier is a test light. should only! have power when the key is placed into the momentary start position. You Dont want it to have power when the key is in ignition or acc. position.)

*black with yellow = ignition coil(should be 12v when the key is in the ignition position, not acc.)

Hook the white 10 gauge wire to the alternator battery "+" post

Assuming you have the typical 12si internally regulated GM alternator:

Get a gm alternator plug from kragen.
put a ring terminal on the red wire. hook that to the "+" battery connection on the alternator
connect the white wire to ignition hot switched 12v. (if you jumper two wires where the voltage regulator was at one point, you can get 12v switched at the original alternator plug. Hook this to the alternator plug white wire. you may need a radio shack sourced diode to prevent run on(I did when I fixed the hacked wiring in the FJ45 I had. solder in so the current flows to the alternator. that means the stripe on the diode goes to the alternator, and the black body towards the wiring harness.

 

[rsc71]

"

"
Actually a larger pulley would make it run slower not faster

Howdy! A bigger crank pulley makes the alternator go faster. A bigger alternator pulley makes alternator go slower. Think about a 10 speed bicycle. John

i think you have it backwards,although you may be going faster down the road the sprockets are turning slower
my rig has the#2 going to the positive post also and have wondered about that.does that mean the alternator is getting exiceted all the time or does it require it to be moving?

 

[inkpot]

i think you have it backwards,although you may be going faster down the road the sprockets are turning slower
my rig has the#2 going to the positive post also and have wondered about that.does that mean the alternator is getting exiceted all the time or does it require it to be moving?

Howdy! A larger crankshaft pulley has a larger diameter. That means more belt travel per one revolution of the engine. Thinnk about that 10 speed bike. Same principal. To go faster, you move the chain to the larger crank ( pedal ) pulley. Same as using larger tires for overdrive. Summit sells just the opposite for hot rodding. Smaller crank pulley and larger alternator pulley so it spins slower and uses less horsepower. Says so right in their ads. John

 

[Downey]

Our V8 instruction manual tells you exactly how to wire the 10SI, but I don't have a copy of it here at home. PM me and i'll take care of this at work on Monday. Normally if you wire the 10SI improperly it can burn out as soon as you apply the power. Evidently your's didn't if it tested ok, probably is not charging battery because not wired correctly though.

 

[jkl72-40]

ok I got it going and its charging well BUT my charge light does not come on and I wired it just like this: How to install a GM Alternator in a Land Cruiser...


why no light??

71 fj55

 

[cruiserjunkie]

is the bulb burnt out?

 

[jkl72-40]

no when it was wired the 1st time it was working just yesterday

does it need a diode???