<VV> High Speed enrichment circuit Carbs - Love them!
Sethracer at aol.com
Sethracer at aol.com
Mon Mar 4 01:13:34 EST 2013
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.
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