<VV> Cold Weather Adjustment

[Mikeamauro at aol.com]

After years of putting up with the cold-natured attributes of my Rochester  H 
model equipped vehicles (conditions under 60-degrees being the most  
troublesome), I finally decided to take a closer look at the issue. Looking  at my two 
H model, powerglide equipped vehicles, and numerous spare  carbs on the 
shelf, I found all had the vacuum choke pull off links adjusted to  open the choke 
too far upon start up. Per various bits of literature, the  ideal positioning 
of the pull off is to have the fast idle on the next to  highest step on the 
cam upon starting with a fully activated choke (i.e.: with  the bi-metal choke 
coils calling for full closure of the chokes). Instead,  what I found was the 
vacuum pull offs, at full cold start, were pulling the  chokes open much too 
far; and, as a result, were also stepping the fast  idle cam well down the ramp 
into the barely useful area of the cam (i.e.:  generally to the next to 
lowest step on the cam). The fix: I straightened the  vacuum pull off links until, 
with choke coils calling for full choke, and  vacuum pull offs activated 
(using a mity vac tool, but one could also push the  pull off in by hand) until the 
fast idle cam was positioned to the next to  highest location. Walah, now, 
even my wife can drive right off on a cold  morning without stalling half a 
dozen times. Using wide band O2 air  fuel instruments, with sheet metal and 
thermostat bellows installed,  excessive choking is NOT evident: AF readings revert 
to lean operation  conditions in about 5-minutes of driving. To achieve the 
desired  adjustments--depending on the individual carb--straightening of the 
pull off  link was required, in some cases, to full straight, and much straighter 
than  seen in any diagrams seen in the manuals and carb rebuild kit  
instructions.  
 
Mike  Mauro          
 
 



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