You folks simply don't know the history of this problem,,
Marvel has been out of business since the early 90's Precision Airmotive of Marysville Wa. bought the production of a very good carb, that had 7 failures to loose venturis.
Precision lawyers used these failures to gain a emergent safety AD from SEA FSDO, to change to a 1 piece venturi, to sell parts thur the ADs system, which cause all the carb that were modified to run rich.
When this was discovered by SEA FSDO the AD was changed to read the 1 piece could be kept and inspected every 100 hours or annual which ever occurred first.
Precision then came up with a new fuel nozzle which made matters worse, and then sold the production certificate to Kelly, who holds it now.
the funniest portion of this is, Kelly has manufactured all the parts for this carb since the 80's .
and they except no part of the responsibility for any of the problem.