Idle Air Vent Opening

[MBP]

Hello. I have a 1969 Rochester #7029207. I was wondering the spec on how far open the idle air rubber flap thingy (technical name) should be at idle. I suspect that it's not to vital since it was done away with the next year but setting up the carb. and wondered if there was a spec. Thanks in advance.

[Kenth]

This:

[Cliff Ruggles]

You are correct by the early 1970's they figured out that venting raw fuel vapor directly to the atmosphere just wasn't a good idea and not needed. 

Here I prefer to leave all the parts in place but carefully bend the wire over to the vent tab so it doesn't open when the throttle shaft closes to the idle position.  No negatives anyplace from doing this.....