New Alternator. Upgrade wiring?

I've installed a Holley Sniper EFI on My B20 Duett. The car has been converted to 12V using the original 6V wiring.
The fuel pump (Bosch 044 clone) pulls nearly 15 AMPS, so I'm upgrading from a 63 amp to a 3 wire 100 amp alternator.
Should I be concerned with the wiring as far as the charging circuit is concerned? Currently while running the voltage runs 12.5 to 12.8. barely enough to keep the battery happy and the stock amp meter is nearly pegged to the "Charge" side.

Thanks for any input
TR

Where do you have 3rd wire?

Positive to battery
Alternator light
Exciter

Check this out

http://www.madelectrical.com/electrical-tech.shtml

Dunno if you mean a three wire Volvo or chevy, or if it matters, but great info in any case

TR Conn said:

Should I be concerned with the wiring as far as the charging circuit is concerned? Currently while running the voltage runs 12.5 to 12.8. barely enough to keep the battery happy and the stock amp meter is nearly pegged to the "Charge" side.

Click to expand...

Can you get a reading from a clamp-on meter to find out what "nearly pegged" means? It might be a pretty low amperage by today's standards. I don't know about Volvo, but I'd guess that all automakers followed a similar pattern of gauge recalibration as electricity requirements increased. For example, Chrysler gauges in the mid-1960s say Discharge/Charge and are calibrated to +/-30A, whereas the mid-70s unit looks nearly identical (to the driver) but calibrates at +/-60A.

Here's a wild ass guess: if the gauge pegs at 15A, and if you wired your fuel pump to the battery side of the ammeter, then yes, it will indicate full charging whenever the fuel pump runs. But the gauge doesn't know that all the juice isn't going to the battery. That situation can be fixed by pulling current from the alternator side of the gauge, instead.

To answer your main question, YES you want to update the wires to handle whatever current you're likely to pull, and YES you want to fuse the alternator lead so that it won't try to dump 100A into your ancient wires if there's a fault somewhere.

Thanks for the replies.
The article you sent the link for is really interesting and in depth. Electrical stuff is one of my weak areas and I' always willing to learn.

In regards to the amp meter, I don't know what its range is, but considering that the original generator was about 30 amps, I guess a 10 to 15 amp range.
I have bypassed the amp meter and wired the alternator directly to the "junction" at the starter. I like this better since it gets the high amp wiring out from under the dash. At this point the charging circuit and the Holley Sniper have been removed from the load on the amp meter. The Holley Sniper is connected directly to the battery as per instructions. The normal functions (WSW, Heater, Lights, Radio) are routed through the amp meter, and until I change the wiring to the meter, it reads backwards. I'm now reading about 13.6 volts at the battery. I've ordered a new voltage regulator to see if that makes a difference.

I'll try out the wiring with the 63 amp alternator. If I'm happy with it, I'll hold the new alternator until I get around to adding A/C.

Again, thanks
TR

FWIW I went thru all of my rigs, upgraded the wiring from stock to #4, saw some significant gains on all 3. Wagon was minimal but there was a little gain, also needed to do it given the 170A Mechman on it. The truck, stock wiring, stock 116A, picked up around .5v while running. 140, replaced the stock #10 with #4, picked up around 0.5v at idle with nothing on, heavy load that upped to almost 1v, with the 100A Bosch on there. Pretty significant gains without doing a ton of work.

Given you've got an EFI system on there, a high draw pump, that 63A alternator may be a bit on the small side if you drive at night with the blower on high.

On my 122 I left all of the existing wiring in place and then built a parallel distribution network for new stuff (which will eventually include EFI), including a heavy additional cable direct from the alternator to the battery.

You lose any accuracy from the ammeter but also IMO much less likely to lose the smoke from the original harness. A voltmeter will tell the story about system health just as well as the light or ammeter.

When I put a Delco alternator on my PV, I replaced all the wiring. And found some really iffy wire junctions along the way that had probably been starving the car of voltage.

So the new alternator probably helped quite a bit, but more than that, the improved wiring.

On my 3 wire setup:
1) Heavy 12V+ wire to battery for charging
2) Warning light/exciter to dash warning light
3) Reference voltage wire to 'other' side of fuse panel

The one-wire setups just hook all three of those together, no warning light.