I was researching the gap to set my spark plugs at, and I noticed something rather odd, just wondering if someone knew the answer.

According to my Chilton manual 99-03 is .060 gap, 04+ is .040

Also i noticed that the spark dwell tables are different between the years
I looked up all 4.8 engines between 2000-2005. the differences are slight, but still, i wonder why they changed....


2000-2003 had this spark dwell


2004+ had this spark dwell

 

I think they have different coils for certain years?? i think? haha

 

I know the plugs are different, the earlier years were platinum which are supposed to be gapped at .060, and then they switched to iridium which are pre-gapped at .040

Funny how the spark dwell tables are different, that may be something for someone with a 99-03 truck to consider if they decide to upgrade to iridium...

 

What plugs are you running, that should help your decision. If you're going with the popular NGK TR55's, you could go with either a .055-.060 gap. I run mine at .055. If factory iridiums, leave them at their factory set gap of .040.

 

I just took my stockers out, they have like 46k on them, but i also have a set of tr55's... I will be running ~10.3-.4 CR with my new heads, and my DCR will be around 8.2-.3.

 

my TR6s are gapped at .035"