Alternator issues on 65

[mustangguy289]

When cruising at night with the lights , fuel pump, and radio on I can only make about 13 volts. At a stop light with the fan turned on this goes to about 10-11V.

During the day cruising can hit 14 volts once up to speed. At stop light with the fan on it will sit around 12 volts.

I currently have a 100 amp alternator ( 60-65 amp was stock) and battery located in the trunk.

Should I replace with 140 or 200 amp alternator?

Electrical items include:
Fuel Pump
MSD ignition
Elec Fan
Radio
factory lighting

[mustangguy289]

http://www.powermastermotorsports.com/ford_early_style.html

I like the 140 amp because it offers the old style look.

[garycrist]

I would ditch the external voltage regulator and up-grade to one of the newer high output alternators. Yes those "little" alternators just do not put out enough.

[Baba Ganoush]

I'm building a '66 right now and I'm adding MSD and an electric fan. I plan to upgrade to a one wire newer style alt. with the internal regulator. I think it's an easy upgrade to the factory harness, but I haven't crossed that bridge yet.

[mustangguy289]

I plan to upgrade to one wire at same time... but what amp? 140 or 200?

[garycrist]

I have a 180 I bought as a kit off Sleasbay for about $170ish. The only mod I did to it was, install a helicoil kit to use the stock mounting bolt.

[mustangguy289]

I have a 180 I bought as a kit off Sleasbay for about $170ish. The only mod I did to it was, install a helicoil kit to use the stock mounting bolt.

What all do you run on your car? Will it hold 14Volts even at a stop light?

At the races today the starting got weaker everytime due to it not able to keep 14v under 2500 RPM.

[garycrist]

Yes! A/C on, dual Contour fans low or high, lights on bright, wipers and radio 14.+V.

[mustangguy289]

How long have you had it? Got a link to it or was it too long ago?

[Aceman85turbo]

I would look to a bad connection somewhere, either a battery cable or ground issue. that alternator should be more than enough. what battery are you using?

[mustangguy289]

I would look to a bad connection somewhere, either a battery cable or ground issue. that alternator should be more than enough. what battery are you using?

An Oreilly's battery.