3G alternator swap ...
 

3G alternator swap issues  

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Dennis111
(@dennis111)
Reputable Member

Over the winter I upgraded my 65 Ford to a 95A 3G alternator using all PA performance parts including their voltage regulator elimination harness. The reason I swapped was because I also upgraded to electric cooling fans.

I keep loosing the alternator/waterpump belt with hard speed shifting at the strip. Don't even get more than 1 run out of it before it either twists on the pulleys or jumps off entirely.

I installed the 4" aluminum racing pulley on the 3G that I have been using for years on the Factory type alternator and also used the same old steel single groove Ford water pump pulley and single groove crank pulley. The old belt that I have used for years needed changed out to one that is 1 1/2" longer to accommodate my swap. The pulley sheeves are all in line with each other.

When it looses the belt, the first indication is that the idle jumps from 1200 rpm's to 2000 rpms. Sounds excessive but the 3G is known to draw more current? Its also easy to spin the alternator/water pump pulleys by hand when the belt is removed.

Has anyone else experienced this problem and how did you handle it???

Dennis
65' STANG, 434W NA, G101A, 4:56 Spool, Victor Heads, Super Vic Intake, Bullet SR, Braswell Carb, 11:1 CR, 3550lbs

9.825@138.00

Dennis
65' STANG, 434W NA, G101A, 4:56 Spool, Victor Heads, Super Vic Intake, Bullet SR, Braswell Carb, 11:1 CR, 3550lbs
9.66@140.65

Quote
Posted : 13/05/2018 4:56 am
Battlestar
(@battlestar)
Famed Member

What kind of rpm? Mine is just a stock Autozone GM one wire and goes 6500 without issue. The belt only runs the alt, I have electric fan.
Have you tried a deep pulley?

Larry
1964 Galaxie wagon
**2006 NORTH Q/S POINTS CHAMP**
**2009 NORTH Q/S POINTS CHAMP**

Canton Automotive Machine
Carls Ford Parts
Hyatt Racing Clutch

Larry
1964 Galaxie wagon
**2006 NORTH Q/S POINTS CHAMP**
**2009 NORTH Q/S POINTS CHAMP**
Canton Automotive Machine
Carls Ford Parts
Hyatt Racing Clutch

ReplyQuote
Posted : 14/05/2018 3:59 am
motorman
(@motorman)
Reputable Member

It happened to me so I did the same thing you did. Bigger pullley on the alternator. Didn't work. The bigger pulley slows down the alternator but the belt was going the same speed. I then went to a smaller crank pulley to slow the belt down and that fixed it.

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Posted : 16/05/2018 12:50 pm
Dennis111
(@dennis111)
Reputable Member

Thank guys. Car gets shifted at 7500 so it runs up to 8K or so before settling down.

Since I want to race all Memorial day weekend I'm doing a Hale Mary on it. I've already installed a throttle switch which will cut out the alternator from about 3/4 throttle to full throttle. Besides lessening the sudden shock from clutchless shifting at the alternator, it will add some HP without the alternator drag.

I have a new set of pulleys and fresh, good brand belts. The old alternator pulley looked worn (5" aluminum that I've used for 10 years) so I got another. Also replacing the waterpump and crank pulleys for ones with deeper grooves. The crank pulley is an inch smaller in diameter so that should help. I haven't had a chance to install it yet as the crank pulley needs a centering adapter made, which is in process.

Dennis
65' STANG, 434W NA, G101A, 4:56 Spool, Victor Heads, Super Vic Intake, Bullet SR, Braswell Carb, 11:1 CR, 3550lbs

9.825@138.00

Dennis
65' STANG, 434W NA, G101A, 4:56 Spool, Victor Heads, Super Vic Intake, Bullet SR, Braswell Carb, 11:1 CR, 3550lbs
9.66@140.65

ReplyQuote
Posted : 16/05/2018 3:36 pm
motorman
(@motorman)
Reputable Member

Keep the alternator working the whole run. You'll be running on 14 plus volts instead of 12.7. The extra hp will more than make up for the drag of the alternator. Thats been proven......

ReplyQuote
Posted : 16/05/2018 4:12 pm
Dennis111
(@dennis111)
Reputable Member

quote:


Originally posted by motorman

Keep the alternator working the whole run. You'll be running on 14 plus volts instead of 12.7. The extra hp will more than make up for the drag of the alternator. Thats been proven......


Since you seem familiar with this I have an alternator drag question. Is there a problem that this alternator (3G) drags the idle down so much when the battery has a full charge?

Dennis
65' STANG, 434W NA, G101A, 4:56 Spool, Victor Heads, Super Vic Intake, Bullet SR, Braswell Carb, 11:1 CR, 3550lbs

9.825@138.00

Dennis
65' STANG, 434W NA, G101A, 4:56 Spool, Victor Heads, Super Vic Intake, Bullet SR, Braswell Carb, 11:1 CR, 3550lbs
9.66@140.65

ReplyQuote
Posted : 17/05/2018 12:08 am
Battlestar
(@battlestar)
Famed Member

quote:


Originally posted by motorman

Keep the alternator working the whole run. You'll be running on 14 plus volts instead of 12.7. The extra hp will more than make up for the drag of the alternator. Thats been proven......


And it begs the question: WHY do some many racers not run an alt and then charge batteries all day? This always boggled my feeble mind. It's bracket racing, dial it in?

Larry
1964 Galaxie wagon
**2006 NORTH Q/S POINTS CHAMP**
**2009 NORTH Q/S POINTS CHAMP**

Canton Automotive Machine
Carls Ford Parts
Hyatt Racing Clutch

Larry
1964 Galaxie wagon
**2006 NORTH Q/S POINTS CHAMP**
**2009 NORTH Q/S POINTS CHAMP**
Canton Automotive Machine
Carls Ford Parts
Hyatt Racing Clutch

ReplyQuote
Posted : 17/05/2018 5:30 am
motorman
(@motorman)
Reputable Member

Draime, my engine builder, built a car for Daytona 500. They are required to run an alternator so they used a gutted one to qualify. then they put the good one on and ran practice laps faster than the ones they qualified with. go figure....the extra voltage helped....

ReplyQuote
Posted : 19/05/2018 2:51 pm
xxbirch
(@xxbirch)
Prominent Member

The best reasons I can think of not to run an alternator are so that it is not in the way of anything, and there is no belt to throw. And then they run a 16 volt battery to keep the voltage up where the alternator would put it.

I run one.

I'd rather shift than win

ReplyQuote
Posted : 21/05/2018 4:03 pm
SuperStockAMX
(@superstockamx)
Noble Member

Been through this. I do believe in alternators as I have tested back-to-back and found no ET reduction even though with no alternator the engine idles faster and revs faster. You’d swear your going to go .05 quicker just blipping’ the throttle! I never saw anything.
I installed a full-sized 16v alternator and I can’t remember how many amps but I went big, like 100 amps? Just because I wanted consistency more than a possible HP gain and there were some other issues I won’t bore you with. But I would lose the belt as I dropped the clutch in the water box at 6,000-6,500.
I guess some would find that in itself excessive?
Anyway, had a cog drive built. Sure looked killer! That took care of the problem.
Now I am changing from Stock to Super Stock and an alternator is no longer a requirement. And now I’m allowed a motor plate. And now with a motor plate, and external oil lines and filter, am finding no room for an alternator! Until I get that re-engineered to fit, I will run dual 16v batteries.

SuperStock / H
1970 390 AMC AMX
Advanced Clutches
Dual 7" Sportsman

1320/MPH=optimum ET!

NHRA SS/H
1970 390 AMC AMX
Advanced Clutches
Single 8” Billet
4300 Autolite
1320/MPH=optimum ET!

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Posted : 22/05/2018 11:55 pm
Dennis111
(@dennis111)
Reputable Member

Weeellllllll, the answer to my engine increasing speed (and me blaming the alternator) was in the 2nd and 4th paragraph of my first post. It was the belt driven water pump pulling the idle down until the belt broke-not the newly installed alternator . . . .

Anyways I found the old aluminum alternator pulley was worn where the belt rides. With that in mind I replaced it with a new larger 5" pulley and changed the 6 1/2" diameter balancer pulley with a smaller 5 1/2" pulley. I also installed a new stock diameter water pump pulley for good measure plus bought a new Napa V belt.

I made sure that all the pulleys were properly aligned with a straight edge in each direction to each pulley. I also added a sturdier alternator bracket and double checked alignment when the belt was installed.

No more belt throwing was experienced after 2 days of racing.

As a side note, I experimented with shutting off the 95A 3G alternator with a throttle switch. When tripped at idle there was no change in RPM's even when the fans were on. I verified that the alternator was not charging by using a voltmeter. When I restored the alternator voltage the output increased to 13.7 at idle with no fans and 14.7 when the fans turned on. I used the switch going down the track and saw Zero differences in the runs. I have since removed the throttle switch as its not needed.

Dennis
65' STANG, 434W NA, G101A, 4:56 Spool, Victor Heads, Super Vic Intake, Bullet SR, Braswell Carb, 11:1 CR, 3550lbs

9.825@138.00

Dennis
65' STANG, 434W NA, G101A, 4:56 Spool, Victor Heads, Super Vic Intake, Bullet SR, Braswell Carb, 11:1 CR, 3550lbs
9.66@140.65

ReplyQuote
Posted : 28/05/2018 4:25 pm
app01
(@app01)
Estimable Member

Great news Dennis and thanks for the other info on the throttle switch. Good to know.

70 Mach 1 Mustang w/ SBF Boss Block 460 Stroker
670HP NA, AED Carb, head/intake work, Duane Busch, Dyno work PK machine, Black Magic Clutches custom softloc, GForce G101a 4-speed, Strange rear, w/4:30 spool,35 spline axles. 3540lbs
best so far is 9.911 @136.86
Build thread http://www.palmiericoncepts.com/My-Mustangs/1970build/Final-Build.htm

70 Mach 1 Mustang w/ SBF Boss Block 460 Stroker
670HP NA, AED Carb, head/intake work, Duane Busch, Dyno work PK machine, GForce G101a 4-speed, Strange rear, w/4:30 spool,35 spline axles. 3540lbs
best so far is 9.911 @136.86
Build thread http://www.palmiericoncepts.com/My-Mustangs/1970build/Final-Build.htm
[IMG">http://www.palmiericoncepts.com/My-Mustangs/signature-small2.gif[/IMG">

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Posted : 31/05/2018 6:16 am
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