<VV> High Speed enrichment circuit Carbs - Love them!

[Sethracer at aol.com]

Hey, Carbmeister!
Fortunately, for the racers, this is a non-issue. When I relocate the main  
jet (And I have done more than 60), the path I use is right through this  
circuit, feeding the carb from this end of the float bowl . When the outer  
plug is removed - on the "enrichment" carbs, I use the hole as the drill 
guide  to drill through to the main well. Much more is done to make it work 
correctly,  but this is the easy way in. Plugged with lead? My drill will go 
right  through, I'm sure. The carb bases I don't like are the ones where Chevy 
saved  .0001 cent by cutting back the material around the base. That makes 
the new  drilling of the passage a bit "tricky". When used on the race cars, 
the jetting  of the carb is based on NO extra enrichment, so elimination of 
this circuit  doesn't matter.   
 
For reference - Rochester called this circuit a "Power System", and said it 
 was used to allow leaner settings for better economy in "part-throttle" 
driving,  with this circuit adding fuel when needed in high air flow 
situation. (I am  still trying to understand the term part-throttle"! <grin>)
 
(Reference: Rochester Carb H, HV service manual bulletin 9D-6 -Sept  1966) 
 
Seth Emerson
 
 
In a message dated 3/1/2013 3:28:40 A.M. Pacific Standard Time,  
gyoungwolf at earthlink.net writes:

Per the  question on whether a carb has an enrichment circuit....all 
enriched carbs  have a rivet near the lower center of the fuel bowl on the pump 
side of the  carb. A very few smog carbs also have them. There is a problem, 
however. If  the carb was ever rebuilt by a big rebuild company, it will very 
likely have  the enrichment circuit plugged with a glob of lead. A dead 
give away is that  they sometimes also plugged the base vent, but the only way 
to be sure is to  take them apart. Sometimes the plug can be drilled out and 
sometimes not, if  the lead found its way into the enrichment jet itself. I 
find dozens of nice  LM carbs ruined this way every  year.