3g alt

[gnpenning]

I've been searchiing the archives and not finding what I want. I have a 74 with a 302 and will be putting in a 3g with v groove pulley. I have read where some are having belt noise. Do you need a 2 groove pulley and then more importantly what would be a part number for one? And yes I have the PS and crank pulleys already. Thank you.

 

[KyleQ]

You don't, did this on my 74' and a bunch of others. I ran it with a single pulley and an automatic and a shitty carb. I used the gear reduction starter non stop and the belt never squealed, never chucked a belt.

Get a 3G, use BC's wiring guide (bridge the one wire, big wire to the charge post and the feed to the battery with the last of the three wires to 12v switched) and then chuck the voltage regulator on the fender and most of the wiring with it.

 

[gnpenning]

Thanks. Are you using a mega fuse with any of these?

edit: I did see the other post on here but it didn't address part numbers.

 

[KyleQ]

I've used a fuse once - found it at Oriley Auto.

 

[707Bronk]

You definately need some sort of high amperage fuse coming off the alternator. It doesn't have to be a mega fuse, but they seem to be common. I am running a 175A mega fuse on mine.

Without fuse protection coming off the alternator, you are taking a huge risk with the higher output 3g alternator.

 

[gnpenning]

Found the fuse just haven't been able to source the holder local. Tried O' Reilly & Auto Zone. Have found them online. Just hate to pay shipping on 1 small item. Thanks

 

[pcf_mark]

If you scrounge the junk yard you may find a max fuse. I think later GM cars have some but my memory is sketchy on that.

I had some squealing on mine with the plane jane Advance Auto belt but then I replaced with a thicker belt that had the ribs on the back and it does not squeal.

 

[KyleQ]

Meh - you don't "need" a fuse or fuseable link, it is just smart. What is funny is that I can get the 175A megafuse at Oriley and I can get the fuse holder at Napa across the street. Neither store carries both, and they are the same brand.. WTF.


I know Oriliey has it, it just isn't on the shelf, you need to ask someone who knows the store, possibly a store mgr. As a temp fix you can put the cable through the hole at the end and twist it around the end - cover it with lots of electrical tape. At least that way you can test the system and have a functioning alternator until you get the holder.

 

[70_Steve]

Meh - you don't "need" a fuse or fuseable link, it is just smart.

There was a member here, RRRAAAYYY2, who ran an alternator and starter shop up in Canada. Pretty sharp guy. Held a world record for the fastest electric motocycle...

He recommended against the mega-fuse. Gave some reasons why, that I don't remember now... So, I took his advice and didn't install one. We'll see how that works out for me... I haven't had a catastrophic failure yet to be able to judge whether the fuse would have helped or not.

 

[garberz]

RRRAAAYYY2 had some good reasons why the fuse is not needed. I fused mine like Chuck's diagram.

A fuse offers no protection against AC noise caused by the alternator. That would be a filter. A fuse rated at 175amps would not blow if the alternator was putting out 16volts at 50amps, but the battery would boil almost instantly. A fuse would not stop a 200volt spike from the alternator, though it could take out every computer in your car. A 175amp fuse will only protect against amperage of over 175amps on the line.

Even a full field situation wouldnt normally cause the fuse to blow. It would still take the alternator reaching over 175amp output before the fuse blows. Most 3gs would not see that kind of output. Under normal driving speeds the 3G would be around 100amps and I am guessing low 20volts under a full field. No battery left pretty quickly, lights would pop if on, etc. Fuse would survive though.

 

[Timmy390]

Found the fuse just haven't been able to source the holder local. Tried O' Reilly & Auto Zone. Have found them online. Just hate to pay shipping on 1 small item. Thanks

Go to a car audio place that sells high output amps and such. I found what I needed there when needing big fuses for my bass boat. No one local had any big holders just the fuses.

Tim

 

[KyleQ]

There was a member here, RRRAAAYYY2, who ran an alternator and starter shop up in Canada. Pretty sharp guy. Held a world record for the fastest electric motocycle...

He recommended against the mega-fuse. Gave some reasons why, that I don't remember now... So, I took his advice and didn't install one. We'll see how that works out for me... I haven't had a catastrophic failure yet to be able to judge whether the fuse would have helped or not.

I thought the same - the only thing the fuse is going to prevent is a amperage spike, and many other things can kill. The fuse is there to protect against accidents and stupid consumer mistakes - not much else.

I don't run them-

 

[gnpenning]

all good info. Still haven't seen any info for a 2 groove pulley.
Thanks

 

[KyleQ]

You don't need a two groove pulley.

 

[Revelation]

Found my Mega fuse at where else, Wal-Mart, in the car audio section.

I run a single pulley and have not had a squeal yet.

 

[garberz]

You don't need a two groove pulley.

Your right, it's that simple. The alternator only will put out what's demanded from it. You'd have to have a lot of high draw accessories all running at the same time to put such a load on the alternator to make the belt squeal.
I run the 3G with one belt, I don't even get squeal at start up. What I need now is a new 3G, because mine just quit on me this week.

 

[dlong]

I'm running a 150 amp resettable fuse that I got from a car audio store.

 

[DirtDonk]

...What I need now is a new 3G, because mine just quit on me this week.

Can you test to see if it's just the regulator? If so, they're relatively inexpensive and relatively easy to replace.
If it's one of our 1-wire conversions, we keep those regulators in stock too, so you won't be left waiting.
For too long anyway! %)

Paul

 

[707Bronk]

While RRRAAAYYY2 is right about the fuse not preventing voltage spikes, a fuse is meant to protect against current not voltage.The voltage aspect is regualted internally on 3g alternators, and if the voltage regulator fails you are unprtected without a fuse. And while alternators create AC current, it is recified via a series of diodes to produce an DC output.

It is the current that lets the smoke out. Failing internals of an alternator and a sudden short on a highly taxed electrical system could let a lot of smoke out.

Wheeling at night with off road lights and heavy winching, with electric fans and fuel pumps on top, you may very well be approaching well over 100amps. And like most people, our electrical systems are one of the last things on our to-do lists, and they are often neglected and hacked and spliced together as is.

Bottom line is, there is no downside to having a fuse, and no upside to running without one.

 

[gnpenning]

Thanks for all the good info. After reading what has been written and past threads it seems that many have no problem with a single belt. Even using good belts with the proper fit some still have had slippage problems so for those who might be following could we have at least one thread that they can find where to get a 2 groove pulley.

Dirtdonk it is so good to see how well our venders look out and take care of their customers.

Thank You.