Without knowing the engine size & model Chevy it is impossible to provide an answer. Look under the hood for a placard with this information listed.
The Spark Plug Gap.060 (In thousandths of an inch)
The recommended spark plug gap on a 1996 Chevy C1500 with a V8-305 engine is .060"
0.035 plug gap
.060
.040 for best results
.060 - 2.2L & 2.4
.045 spark plug gap
The spark plug gap is listed in your owners manual and under the hood on a placard.
65
0.060 Inch
Spark plug gap chevy ls blazer
The Spark Plug gap is .045