Recall - Incorrect Compression Ratio/PROM Update: Overview

Number: 87C09

Section: 6E

Date: July, 1987
Subject: PRODUCT EMISSION CAMPAIGN 87C09
INCORRECT COMPRESSION RATIO


Model and Year: 1987 G 30 VAN OVER 8,500# W/5.7L ENGINE (RPO L05, VIN CODE K) AND 3 SPEED AUTOMATIC TRANSMISSION (RPO M40)
TO: ALL CHEVROLET DEALERS

General Motors has determined that certain 1987 G 30 model vans may have been produced with an engine compression ratio of 9.3:1 rather than 8.6:1 as intended. While there is an improvement in performance, this condition may result in spark knock.

To minimize the possibility of spark knock, new PROMS have been released with revised spark advance calibrations which will allow proper engine operation at the increased compression ratio.