OK, so I'm hearing the GM issued a service bulletin at some point (maybe several years ago) that says to no longer use the recommended .60 gap on vehicles that show that under the hood and instead start gaping plugs at .40 or .45 (I don't remember which).

Supposedly .60 was too hot and caused issues with ignition system components so either .40 or .45 works better.

I have several vehicles, but right now I'm needing to replace plugs on my '03 S10 with 4.3L and I noticed on Rock Auto.com shows AC-DELCO 41993 Professional Iridium being gaped at .60 but it shows DENSO 5325 Iridium Power being gaped at .44

Can anybody verify what GAP should be used for a 2003 4.3L engine?

 

0.44 will be fine

My experience you wont have idle or misfire issues until you get to the mid 20s range. Too large of a gap also causes misfires, which is probably why they changed it from 60 to 45.

 

I was hoping to find an official quote from GM on this...