I just dropped in a 350/290 crate in my 70 nova.Everthing seemed to be fine but my alternator only charges when I'm above 1300rpm,when they drop it stops charging.I never had this problem before its a stock late 70s internal reg. alternator.The engine temp goes up quickly even though I have my ele. fan set to 160' is this common for a new motor?  

Are your pulleys same as used before? If so,try changing alternator. Do you have fan wired so it don't drain from charging current? It is most likely alternator went bad unexpected.  

I ordered a 100A alt. from summit.My fan runs through a relay and a circut breaker.What do you mean about it draining from charging current,how should i wire it?I do remember the voltage at the batt droping when the fan came on,and I did set the fan to come on at a low temp. to keep the new motor cool.