Electrical problem help?

[Grandprixpaul]

I' ve recently did a major engine swap And I'm haven some problems , everything on engine is new now, I have a 1987 grand prix had a 4.3 in it , replaced with a 350 sbc,, 366hp the alt light is coming on and the car wont hold a charge but I have a 180 amp alt. Had it tested to make sure its working properly, and a mini hi torque starter , had that tested to, but car still loosing charge on a new battery, went over wiring twice and I must be missing something any help? Ideas,..........

 

[megaladon6]

first, get a multimeter and make sure you have 12.6v at the battery with the car off, then start it and see if you have 13.6v (preferably more) and if it fluctuates with RPM. then test at the alternator, it should be closer to 14.4v.
also, make sure you have the right alternator--that it's spinning the right way.
how many wires does the alt have? pics would be great as there are many versions. also how is it wired?