just got back from tuning and i noticed this noise, only happens sometimes and only off of idle, still revs to 7500 and makes power


91 rx7 engine noise - YouTube

 

why do you only have ONE belt running the alternator and water pump?
sounds like belt backlash.

 

currently that is the only belt i have and tomorrow im going to check that but it doesn't seem to sound like that to me, hopefully im wrong

 

ok, so it was the belt, thank god

 

Find a dual alternator pulley and put 2 equal sized belts on then.
That is what they do when they delete the air pump.
It is actually a good thing to do as #1: it is a security that if one belt breaks the other still provides to the pump and alternator.
#2 is it prevents the Water pump and alternator from slipping.

 

already have the pulley on and i just got the 2 belts last night