Mike Carter
Well-known member
yep, clamp on ammeter best bet.
Mike
Mike
MaineShark
Well-known member
- Joined
- Sep 21, 2002
- Messages
- 1,326
- Location
- Rockingham County, NH
- Corvette
- 1979 L82, 1987 Buick Grand National
FYI, I just priced a replacement alternator. A local shop will sell me one of the new-style (small case), 100-amp alternators, factory-remanufactured, for $110. Actually, the alternator is $95 - the rest is the new plug, and the tax.
There are a variety of different mounting-bolt positions on the new-style alternators, but there are some that have the same bolt spacing as our alternators, so they will drop right in without new brackets. That's something to make sure they check - the first one he grabbed off the shelf had a different hole spacing. But he did the right thing: pulled out the correct alternator for the '79, and then compared hole spacing to make absolutely sure they were identical.
All that it seems is necessary, is to swap out the serpentine pulley for my V-belt pulley, splice in the new plug, and replace the main power wire.
I didn't get it yet, but I think I'm going to run by tomorrow and grab it, so I can get it installed immediately, while I have everything apart.
Joe
There are a variety of different mounting-bolt positions on the new-style alternators, but there are some that have the same bolt spacing as our alternators, so they will drop right in without new brackets. That's something to make sure they check - the first one he grabbed off the shelf had a different hole spacing. But he did the right thing: pulled out the correct alternator for the '79, and then compared hole spacing to make absolutely sure they were identical.
All that it seems is necessary, is to swap out the serpentine pulley for my V-belt pulley, splice in the new plug, and replace the main power wire.
I didn't get it yet, but I think I'm going to run by tomorrow and grab it, so I can get it installed immediately, while I have everything apart.
Joe
MaineShark
Well-known member
- Joined
- Sep 21, 2002
- Messages
- 1,326
- Location
- Rockingham County, NH
- Corvette
- 1979 L82, 1987 Buick Grand National
Alright, I didn't actually get the alternator Saturday, like I planned.
But I did trace the power wires in the wiring diagram.
It looks like the best method for adding auxilliary connections in this car is to replace the alternator-to-starter wire with a heavier wire (that is, cut the existing wire, and add a second wire directly from the alternator terminal to the starter - unless you plan on yanking your whole wiring harness apart), and then add a second fuse box for the auxilliary loads, also connected to that main terminal on the starter.
My wiring diagram shows the power wire as being 12ga wire. So, looking up the amp ratings, I'd say that 8ga would be fine to make the alternator-to-starter run (10ga would work, too), and 12ga would be plenty to run from there to the second fuse box.
"But those wires aren't rated for 100amps!" you say.
No, they aren't (except for very short runs), and they won't see it, either. Remember that current only flows where you pull it. And the alternator wire splits into several separate 12ga runs that go to various connections within the car. So no one of those wires carries the full current - each draws only what it needs.
The stock alternator is supposed to be rated for around 60 amps, from what I hear. So a 100amp alternator is a 40amp improvement. Look up 12ga wire, and you'll find that it's rated for around 40amps. Add another 40, and you're up to 80. So, figure that this is the new draw through the alternator-to-starter wire, when the acessories are all drawing their full potential. Look down to find 80amps, and you'll see 8ga as the wire.
So, 8ga to the starter. Then 12ga to the new fuse panel, since it will handle the 40 amps which that run will see.
And there you have it.
Now, I just need to get the alternator and wire, and hook it all up.
And remember: the alternator wire that you see actually splits off inside the harness. Unless you plan on pulling the harness apart, leave that wire connected, and just add your new wire to the starter as a second wire. If you'd prefer a cleaner look, you need to yank the existing wire, all the way back through the firewall to the junction. Personally, I think that's more work than I want to do.
The "halfway" method would be to create your own junction by cutting the wire somewhere inside the loom, running your new wire in, splicing the old wire off the new wire, heat-shrinking the connection, and then closing the loom. That way, your 8ga wire will run from the alternator to the starter, and the existing power lead will draw off it, but be hidden inside the harness.
Joe
But I did trace the power wires in the wiring diagram.
It looks like the best method for adding auxilliary connections in this car is to replace the alternator-to-starter wire with a heavier wire (that is, cut the existing wire, and add a second wire directly from the alternator terminal to the starter - unless you plan on yanking your whole wiring harness apart), and then add a second fuse box for the auxilliary loads, also connected to that main terminal on the starter.
My wiring diagram shows the power wire as being 12ga wire. So, looking up the amp ratings, I'd say that 8ga would be fine to make the alternator-to-starter run (10ga would work, too), and 12ga would be plenty to run from there to the second fuse box.
"But those wires aren't rated for 100amps!" you say.
No, they aren't (except for very short runs), and they won't see it, either. Remember that current only flows where you pull it. And the alternator wire splits into several separate 12ga runs that go to various connections within the car. So no one of those wires carries the full current - each draws only what it needs.
The stock alternator is supposed to be rated for around 60 amps, from what I hear. So a 100amp alternator is a 40amp improvement. Look up 12ga wire, and you'll find that it's rated for around 40amps. Add another 40, and you're up to 80. So, figure that this is the new draw through the alternator-to-starter wire, when the acessories are all drawing their full potential. Look down to find 80amps, and you'll see 8ga as the wire.
So, 8ga to the starter. Then 12ga to the new fuse panel, since it will handle the 40 amps which that run will see.
And there you have it.
Now, I just need to get the alternator and wire, and hook it all up.
And remember: the alternator wire that you see actually splits off inside the harness. Unless you plan on pulling the harness apart, leave that wire connected, and just add your new wire to the starter as a second wire. If you'd prefer a cleaner look, you need to yank the existing wire, all the way back through the firewall to the junction. Personally, I think that's more work than I want to do.
The "halfway" method would be to create your own junction by cutting the wire somewhere inside the loom, running your new wire in, splicing the old wire off the new wire, heat-shrinking the connection, and then closing the loom. That way, your 8ga wire will run from the alternator to the starter, and the existing power lead will draw off it, but be hidden inside the harness.
Joe
- Thread starter
- #44
C
clar2001
Guest
Thank you for putting it in simple english, I was confussed with all the debate,I have purchased every thing except the alt . seem to be having a bit of a problem finding a new crome 100amp. alt.
85 and 140 our popular ,the closest I have seen is summit, one that puts 70amps at 800rpm and 100amps at 1500rpm for I think it was $120
The 75 vette has been in pieces for three weeks now and i'm looking at anouther two it hard to keep spending money and not drive it .
Thanks Joe & every one else for the input you guys our helping me do this right, signed a self tought menechic becides it no fun to let some one else work on your car.
Clar2001
85 and 140 our popular ,the closest I have seen is summit, one that puts 70amps at 800rpm and 100amps at 1500rpm for I think it was $120
The 75 vette has been in pieces for three weeks now and i'm looking at anouther two it hard to keep spending money and not drive it .
Thanks Joe & every one else for the input you guys our helping me do this right, signed a self tought menechic becides it no fun to let some one else work on your car.
Clar2001
Jack
Well-known member
- Joined
- Dec 27, 2000
- Messages
- 1,825
- Location
- Florence, SC (Timmonsville SC)
- Corvette
- 71 War Bonnet Yellow VERT 71 BH Blue CPE (SOLD)
Chrome looks great but it holds heat in ... alternators will live longer if not chromed.
JACK:gap
JACK:gap
SPANISHVETTS
Well-known member
- Joined
- Nov 5, 2002
- Messages
- 1,143
- Location
- El puerto de Santa Maria Spain
- Corvette
- before 60,63&82 now 90 383 Stroker & 91 ZR1-Sold
Have a look at this.
I put the IceBurg kit on my 90 last fall. So far it has ended all of my C4 alternator problems. The weather has been in the 90´s here for about 6 weeks and I have put a couple of thousand city, traffic miles on the car still no problems.
The SI series of alternators were much better built than the CS series that started around ´86. an upgraded 12-SI should give you all the power you will ever need and will drop in place with no modification.
I put the IceBurg kit on my 90 last fall. So far it has ended all of my C4 alternator problems. The weather has been in the 90´s here for about 6 weeks and I have put a couple of thousand city, traffic miles on the car still no problems.
The SI series of alternators were much better built than the CS series that started around ´86. an upgraded 12-SI should give you all the power you will ever need and will drop in place with no modification.
Similar threads
Corvette Forums
Supporting Vendors
Dealers:
