<VV> Carb adjustments

[Sethracer at aol.com]

In a message dated 4/4/2009 12:09:57 PM Pacific Daylight Time,  
sharpiebandit06 at bellsouth.net writes:

I've  been on this for hours playing with the fueld needles and idle screws, 
please  help me?

also, does anyone know where I could get some velocity  stack that would fit 
the single carbs?

1965 Monza 95hp PGCharles  Birchwood Ps. 121
"Nullius addictus judicare in verba magistri"-Horace  





My Latin is a little rusty (9th grade, Mrs. Dingham, 1962)
 
Does that mean "Adjust carbs only after verifying the correct ignition  
advance setting, done with the vacuum line removed and plugged"   Good! 
 
The shop manual has a great write up on how to adjust the carbs.  
Essentially, though, you disconnect the cross shaft from the left hand carb.  When you do 
that, the big throttle return spring is disconnected from the left  side 
carb, that's why Smitty suggested the rubber band. The first issue to  address is 
making the carbs split the load at idle. There is a tool called a  Unisyn 
which sits down on the top of the carb and measures the amount of air  being 
ingested. It measures relative flow, so, at idle you hold it on top on one  carb, 
then the other. If you start off with the idle MIXTURE screws about 1 and  1/2 
turns out from seated, the engine should idle enough to adjust the idle  SPEED 
screws. A good starting point for the speed screws is about one-turn in  from 
initial contact with the linkage. Make sure the chokes are thoroughly off  so 
other linkage does not interfere. Then, using the unisyn - you can also  do 
this with a vacuum gauge attached to the horizontal tube on the carbs - the  
tube usually has the choke pull-off hose attached to it. Basically, when  the 
flow volume into the engine is the same at both carbs, then you can  raise or 
lower the idle rpm by making the same exact adjustment to both carb's  idle 
speed screws. Once you have the idle speed you want, check again to make  sure you 
have equal flow through both carbs. Only them should you be adjusting  the 
idle mixture screws. For a street car, I use the lean-roll method, developed  to 
meet smog rules in the 1960's. With a low-speed tachometer showing the idle  
RPM, screw the screw it just enough to see the RPM drop slightly, (I then open 
 it outward 1/8 of a turn) and do the other side. In a performance 
application,  you still hook up the tach but adjust the mixture to the highest idle 
speed,  then do the other side. You may have to make a further adjustment to the 
idle  speed screws at this point.  Make sure you don't have any vacuum advance  
applied at idle.
 
Velocity stacks are not needed for the Corvair in street use. But  there are 
several K&N type bolt-on filters that will work with a slight mod  to the 
clamping flange.  Please be kind and route the smog tube into the  air filter.
 
 
Seth  Emerson

C's the Day! - Corvair, Camaro, Corvette



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