put a holley 58mm t-b on my lt1 and now it won't idle down unless i tap the gas. the throttle cable seems to work good no binding.is there something else that needs to be changed when changing the t-b.or do i just need to adjust something? if so what?

 

maybe to much air going in at idle?...that T/B doesnt have much to support so it isnt like ur engine is feening air

 

Did you check the TPS voltage? Do you have a way to check the IAC position?

Read this thread:
http://web.camaross.com/forums/showthread.php?t=459834

Looking at your signature, I don't think you needed a 58mm throttle body, did you?

 

Common problem:

http://camaross.com/forums/showthread.php?t=462614

 

thanks you're right the spring is a wimp.going tighter worked, the blades looked good. again thank you