<VV> Rochester Idle Circuit Inconsistencies

[Mikeamauro at aol.com]

I've noticed a propensity for H-Series carbs--early or late--to have  
transient idle circuit inconsistencies; the situation I describe goes for  carbs 
thoroughly soaked in carb cleaner, overnight, and then having all passages  blown 
out with compressed air, then rebuilt...as-well-as carbs having been  in 
service for some time.  Issue Description: (assumes side-to-side air  flow is spot 
on, as verified by Unisyn) The idle may be smooth for several days,  or 
months, and then all of a sudden idle becomes rough and engine wants to "die"  at 
idle. Simply revving the engine sometimes clears the issue. Otherwise,  removing 
air cleaner; revving engine, and momentarily cupping hand over carb air  horn 
sometimes clears the issue and idle returns to normal. However, more often  
than not, the required fix is to remove idle mixture screw and squirt carb  
cleaner and/or compressed air into the hole from which the idle mixture screw  
was just removed. Reinstall mixture screw; adjust, and all is well...till  the 
next time. Why is this happening? This has been a fairly regular  occurrence, 
on two different vehicles, over a number of different carb  rebuilds, using 
different cores, over many years of Corvairing. Has anyone  else observed this 
situation? I surmise flaking may be occurring in  the idle circuit passages, and 
the increased velocity imparted by: revving,  revving & cupping air horn, 
and/or blowing through the circuit may be  dislodging the offending, obstructing 
flakes. Other opinions or ideas, for  a long term solution, would be 
appreciated. 
 
Thank you,
Mike Mauro     
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