Spark plug specification question

2000 Silverado, 4X4, 5.3 L

My owners manual calls for a 41-952 spark plug with a gap of .060, I know this was later changed to a 41-974. I just bought new plugs and got 41-985's with a gap of .040 (clearly marked "do not change gap"), I checked with a dealer and was told these are correct.

Does anyone know why this change was made? Seems strange because now the emissions label is incorrect. I found some other brands (NGK for one) which still have the.060 gap. Any reason to pick one over the other?

Thanks, Al

Reply to
ajtessier
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there may have been a problem with the original spec plugs for that engine. It's common in engineering to refine specs over the production run of a design.

Reply to
daniel ferguson

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