Full Size Chevrolet V8-305 5.0L (1984)
Spark Plug: All Technical Service Bulletins
Ignition - Spark Knock (Pre-Ignition)
Number:
85-199
Section:
6D
Date:
APR., 1986
Subject:
REVISED SPARK PLUG RECOMMENDATION FOR PREVENTION OF DETONATION
Model and Year:
1984-85 CAPRICE/IMPALA WITH
5.0L (VIN CODE H) OR 5.7L (VIN CODE 6)
TO:
ALL CHEVROLET DEALERS
Customer comments may be received regarding detonation induced preignition on 1984-85 Caprice or Impala models with 5.0L
LG4 or 5.7L LM1 engines. Detonation is most likely to occur when the vehicle is pulling a grade or in extended periods of heavy
load operation and may lead to preignition which can be recognized by melted spark plug center wire.
If normal diagnostic procedures do not correct the cause of the detonation, the original spark plugs (R45TS) should be replaced
with R43CTS plugs, P/N 5613810. These plugs have a colder heat range but are equipped with a copper core to reduce plug
fouling.
Spark plug gap should be set at .035".
Use applicable labor time and operation number.
