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Alternator help help
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jag327
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Joined: 04 Jun 2009
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Location: PG County MD
3218.32 points


1982 Chevrolet Camaro

PostPosted: Tue Sep 28, 2010 11:23 pm    Post subject: Alternator help help Reply with quote

Hi guy's, I'm back again. Ok now I have bought a 140 amp 3 wire power master, When the fans kick in the the rpm drops 400 to 450 rpm I have tried re-wiring the alternator change the belt it still did the something.

So I bought a tuff stuff CS130 a 160 amp alternator this would drop 2.5 to 300 rpms only when the fans kick my idle is at 800 rpm this is a 1 wire type alternator.

I added a ground wire to the alternator, 1 ground wire to the motor and 1 to the frame, I up the alternator wire to the battery 4 gauge it still drops.

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10sec.et
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1969 Oldsmobile Cutlass

PostPosted: Wed Sep 29, 2010 2:01 am    Post subject: Reply with quote

have your battery load tested and double check your battery terminals/cables. if either are bad, your alternator will be trying to power everything by itself.
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jag327
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Joined: 04 Jun 2009
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Location: PG County MD
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1982 Chevrolet Camaro

PostPosted: Wed Sep 29, 2010 12:05 pm    Post subject: Reply with quote

[quote="10sec.et"]have your battery load tested and double check your battery terminals/cables. if either are bad, your alternator will be trying to power everything by itself.[/quot

All new wiring and double check, 2 - O gauge ground wiring 1 to the frame and 1 to the motor, 6 gauge main wiring going to the fuse box,
from the plus side of the battery, alternator has 4 gauge wiring going to the plus battery side and 6 gauge wiring mount to the back of the alternator going to ground.

I will install another battery to check, my volts read on the gauge in the car 13 volts and 12 to 12.5 when the fans kick in when I turn the head lights on it drops a little lower and my rpms drop another 150 rpms.

You no of any problems like this when fans kick in rpms drop and voltage.

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jag327
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Location: PG County MD
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1982 Chevrolet Camaro

PostPosted: Wed Sep 29, 2010 2:12 pm    Post subject: Reply with quote

I was told my timing was to low 12 total 38 motor not turning over the alternator under a load I was told take up 16 and see what happens
this the 1st I herd this....

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Big Dave
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PostPosted: Wed Sep 29, 2010 11:14 pm    Post subject: Reply with quote

You are out puting 2000 Watts of power at a minimum. How much do the fans draw? (reworded you have 160 amps on tap what size fuse do your fans have?)

I dobt that the fans are drawing enough horse power to kill your engine unless we are talking a Go Kart with a Briggs and Straton engine. Figure at about 40 Amps on the fuse the most you could draw without poping the fuse would be a little over a horsepower. I'm pretty sure your motor isn't down in the fractional area just yet (even a 3-1/2 horsepower B&S lawn mower engine could keep those fans running all day figuring a 40% efficency through an alternator on conversion of mechanical to electrical and back again).

Big Dave
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jag327
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1982 Chevrolet Camaro

PostPosted: Wed Sep 29, 2010 11:40 pm    Post subject: Reply with quote

Big Dave wrote:
You are out puting 2000 Watts of power at a minimum. How much do the fans draw? (reworded you have 160 amps on tap what size fuse do your fans have?)

I dobt that the fans are drawing enough horse power to kill your engine unless we are talking a Go Kart with a Briggs and Straton engine. Figure at about 40 Amps on the fuse the most you could draw without poping the fuse would be a little over a horsepower. I'm pretty sure your motor isn't down in the fractional area just yet (even a 3-1/2 horsepower B&S lawn mower engine could keep those fans running all day figuring a 40% efficency through an alternator on conversion of mechanical to electrical and back again).

Big Dave


it has a 40 amp fuse it never pop, Tried a power master 140 amp
1500 rpms fans kick in rpm would to 1100 to 1000, at 800 rpm it would drop to 500 until the motor cut off. this a 12si type... 3 wire.

I have a tuff stuff now 160 cs130 bull it runs better but the rpms
still drop but not like the power master

My crank pulley is about 6.5" wide from top to bottom or lip to lip.
inside V groove take off the lips could be about 6" wide

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Big Dave
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PostPosted: Thu Sep 30, 2010 9:20 am    Post subject: Reply with quote

746.27 Watts equals one horsepower. You have a Nominal 12.5 Volt electrical system (though with a charging battery, voltage should measure 14.3 Volts) so if you multiple 40 Amps by your measured voltage you get the number of Watts of power you are producing. 40*12.5=500 Watts. Divide the 500 Watts by 746.27 and you get 0.667 horsepower or 2/3 of a horsepower. That is the total load your fan is pulling off your electric grid, but due to inefficiencies in converting mechanical energy into electrical energy and then back again figure closser to one horsepower being pulled off of your motor whenever the fan's activate.

I will leave you to ponder that fact. But I doubt that the fan is your biggest problem.

Big Dave
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af2
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1933 Willys Coupe

PostPosted: Thu Sep 30, 2010 7:38 pm    Post subject: Reply with quote

Now you take the 2" pulley and the 8" pulley you have increased the HP by how much?? HMMM. It is more than what you would think.

Dave?
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Skunkworkx
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1968 Chevrolet Camaro

PostPosted: Thu Sep 30, 2010 9:58 pm    Post subject: Reply with quote

Have you thought about a solenoid (like on AC cars) to bump the idle up when the fans go high ? Cheaper/easier fix Smile
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10sec.et
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1969 Oldsmobile Cutlass

PostPosted: Fri Oct 01, 2010 2:55 am    Post subject: Reply with quote

im with Dave. ive watched the RPM on cars while the AC and fans turn on and its barely 100 RPM loss. put it in gear with AC, fans and headlights on and you get maybe 200 RPM drop. there is certainly more going on than just fans and alternator. could be a really lousy tune. ive seen cars with carbs so lean that they wouldnt hold idle if you turned on anything. granted, they were POS smog engines that were lean to start with but still....
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jag327
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1982 Chevrolet Camaro

PostPosted: Fri Oct 01, 2010 11:34 am    Post subject: Reply with quote

10sec.et wrote:
im with Dave. ive watched the RPM on cars while the AC and fans turn on and its barely 100 RPM loss. put it in gear with AC, fans and headlights on and you get maybe 200 RPM drop. there is certainly more going on than just fans and alternator. could be a really lousy tune. ive seen cars with carbs so lean that they wouldnt hold idle if you turned on anything. granted, they were POS smog engines that were lean to start with but still....


I could set the idle at 1500 rpms when the fans kick in it will slowly drop to 1100 rpms to almost 1000 rpms

The motor runs very strong no misses strong bills all the way to 7500 rpms.

I have a quick fuel carb at idle it runs a little rich but that should not
have anything thing to do rpms dropping right. It will idle 800 easy no dropping with out the fans being on the cam shakes the car a little or lights being turn. only the fans and the rpms drop.

youtube video fans on when I turn them off rpms going up.

http://www.youtube.com/watch?v=n49dmII6cIY

I had few multimeters but could not find 1 of them . I will run up to
harbor freight and pick up today.

Man the car ran good all this summer but have this last bug to work out.

I will say this I do like 3 wire alternators better.

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af2
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1933 Willys Coupe

PostPosted: Sat Oct 02, 2010 7:17 pm    Post subject: Reply with quote

A shot in the dark.

Would the Power valve by chance be on the edge of opening? Then the drop in idle brings you below (vacuum) and goes down from there?
You need a vacuum guage. There is a lot of ways to diagnose if you have one.
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af2
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1933 Willys Coupe

PostPosted: Sat Oct 02, 2010 7:20 pm    Post subject: Reply with quote

jag327 wrote:


I have a quick fuel carb at idle it runs a little rich but that should not
have anything thing to do rpms dropping right.



I meant to quote this! Laughing
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clay
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1972 Chevrolet Nova

PostPosted: Sun Oct 03, 2010 1:17 am    Post subject: Reply with quote

Power valve opening shouldn't have an effect on idle. If it is leaking through the diaphram or past the gasket it would cause a problem but it would be full time. I do agree with af2 through, a vacuum gauge and a voltmeter would help. Clay
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jag327
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1982 Chevrolet Camaro

PostPosted: Sun Oct 03, 2010 11:07 pm    Post subject: Reply with quote

I have a vacuum gauge in the car and I mount 1 to the intake 4.5 vacuum at 800 rpm.

I hook up a multimeter

Battery set for 5 days volts 12.57

Run motor cool temp 140 - at 800 rpm volts 14.35 at the battery +/-

Run motor temp at 180 volts 14.22 at the alternator at the battery volts 14.15

Run motor temp 195 fans and head lights on volts 13.87 to 14.06

rpms drop 100 and stayed there so I let the motor run fans and my lights on about 12 mins of running time the rpms dropping to 200 to 300 rpms check volts - 12.34 to 12.56 alternator hot to the touch - so the fans are pulling from the battery.

I rev the motor up to 3000 rpms volts 14.6

My carb has a 4.5 power valve - my vacuum at 800 rpms is 4.5

I no the power valve should be 2.0 the motor ran very good this summer so I lift it alone. "O" my jets 74/84 my 4 conner idle crews are about 1.5 turns out if I change the 74 jet to 73 the motor around 6200 kinda hesitate 74/84 motor runs very stong.

It seems to me when the alternator runs for 18 mins or more at idle shuts down when getting hot or just not putting the amps out to keep everything running. My cam tone changes like
the plugs are getting weak but when I turn the fans off it runs the way it should.

What you guys think.

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