1967 - 1968 Corvette: Engineering Service Note: Idle Cooling and Dieseling on Corvette with 427 CU IN Engines
Subject: Idle Cooling and Dieseling on Corvette with 427 CU IN Engines
Model and Year: 1967 - 1968 Corvette with 427 Cu. In. Engine (#844) (D.S.T.)
Source: Chevrolet Engineering Service Letter - UPC VI - Engine
Page Number: NA
Date: May 1968
The 1968 Corvette with 427 cu. in. engine, air conditioning and manual transmission is being changed in production to improve idle cooling as follows:
1. Changed distributor vacuum advance control from "ported" spark to full manifold vacuum.
2. Increased idle speed to 1000 RPM with air conditioning "On".
3. Added anti-dieseling solenoid usage can also be extended to non-air conditioned 1968 427 cu. in. engines as well as 1967 Corvettes with 3 x 2 carburetors.