<VV> Rochester Idle Circuit Inconsistencies

[Rick Loving]

Sounds like the flaking may be from inside the gas tank or inside the lines
coming too the carb.

Do you have an AUX inline fuel filter and where is it?  How old are the hard
lines from the pump to the carbs?

I had similar problems on a 65 Corsa barn car that didn't go away until I
replaced the lines in the engine bay "after" my inline filter.

The carbs and stones had been completely gone through and cleaned several
times before the lines were replaced and the problem "went" away.

Rick Loving


Subject: <VV> Rochester Idle Circuit Inconsistencies

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