1966 Corvette: Engineering Service Letter: Corvette 427 Mark IV Engine Surge (No. 358-T.I.)
Subject: Corvette 427 Mark IV Engine Surge (No. 358-T.I.)
Model and Year: 1966 Corvette 390 H.P. 427 Mark IV Holley Carburetor
Source: Chevrolet Engineering Service Letter
Bulletin No: TNP #66-2
Section: Section VIm
Some early Corvette 427 Holley carburetors were built with lean metering jets. Because of this, engine surge may be encountered between 40 to 60 mph during light to moderate acceleration.
To satisfy field complaints, replace the #63 metering jet with the #65 P/N 2193938.
Carburetors with build date code including and after 594 incorporate the richer jet.
The build code is stamped below the Chevrolet part number located on the carburetor air horn. The first digit is the year, the second - month, and the third digit is the week of the month.