I started having charging system troubles on the Daytona last week,
and this one currently has me stumped. Car is an 86 Daytona & had the
original style alternator on it. Evidently the voltage regulator
started acting up in the PM, causing sporadic problems. Finally the
other day it must have full fielded the alternator as it's toasted. it
got HOT. So I've got a friend who owns a starter/alternator shop and he
hooked me up with a 120 amp ND alternator and a two wire external
regulator. The regulator is a Transpo unit and has a pot adjustment on
the back to fine tune the voltage. I've mounted the alternator, went
ahead & ran an extra 8 gauge ground from the alternator case to the
negative battery terminal, and mounted the regulator. One wire on the
regulator is key switched, and the other wire goes to one of the small
terminals on the alternator. The other small terminal on the alternator
is grounded with a small loop that hooks it to the same spot that I
grounded the alternator case. Now here is the problem.. I can make it
charge, but anything above about 1500 RPM and it's running the
alternator wide open. I've tried turning the regulator down with the
adjustment, I've ran a ground from the regulator case to the battery &
and no changes. It really has me stumped.

I think the next step is to run a new wire from the post on the
alternator directly to the positive post on the battery & probing the
old wires if I can find my good meter. I've never seen one act like
this, and my alternator shop friend is stumped by it as well. Both the
alternator & the regulator test out fine on a bench tester. Ideas
anyone?