Triumph Repair: Defective Generator, voltage drop test, dash light

Question
I just installed a rebuilt generator in my '64 TR4, it is now charging the battery but I have developed a pretty severe performance problem.  The engine doesn't like more than 1/4 throttle - hesitation, backfiring etc.. If I unplug the small wire from the generator, the car runs well but of course the red dash light is on.  How can this generator be effecting performance.  Thanks, Pete

Answer
Hi Peter,
I would first check the ground strap between the engine and the frame and the battery ground strap for a good ground not just tight. A voltage drop test is best.
Next put a volt meter across the battery posts and set the throttle at about 1500 RPM (with the small wire attached) you should have 13'8 to 14.5 volts but not higher. If it is higher then you have a regulator and/or a generator problem.
let me know,
Howard