This would be easier to answer if you told us what engine you have. It should be printed on the VECI label. The VECI label, if destroyed, can be purchased from your local GM dealer. It usuaslly costs about $12, but sometimes they give it to you for free.
Failing that, it's probably .035 but might be .042. Go with .035 and it'll ride up with wear.
If you buy AC Rapidfire plugs or any good brand of platinum plugs, they will be pre-gapped. Bosch is not a good brand of plugs unless you like to burn wires and coil boots. Instead, go for Autolite, NGK, Denso, Motorcraft, AC, or even Champion first.
The recommended spark plug gap is .045"
The spark plug gap is .045.
Gap it at .60
The spark plug gap for a 1989 Honda Civic LX is .044" (1.11mm).
The spark plug gap for a 1989 Toyota Camry is usually preset when purchasing a new spark plug. However if not preset, then the gap should be set at .044 inches.
On the 3.3 Liter V6 it is .060.
Per Champion spark plug applications chart, the gap for 1989 Chevy 305 (5.0L) is .035.
1989 Mazda 626 2.2L FI 4cylThe Spark Plug Gap.044 (In thousandths of an inch)
The spark plug gap for your 1989 Chevy Celebrity 2.8 V6 is .045".
.060 of an inch
The spark plug gap for a 1989 Honda Civic with a 1.5 liter engine should be set at .044 inches. Most Honda engines have a spark plug gap of .044 inches.
The 1993 Oldsmobile Cutlass 3.1 liter engine spark plug gap is .028. Most spark plugs will come pre-gapped from the manufacturer.