Spark Plug Gap

[Supraman]

The factory plugs in our engines were Iridium Denso 3297 SK20R11. These have a preset gap of .044

Typically everyone has agreed, including myself, that Iridium is not necessary and we're much better off going with basic copper plugs and changing them out yearly.

One of the common recommendations is to use the plug for a 2000ish Toyota Tundra 4.7L. This would be an NGK 6364 which has a gap of 0.032.  Or in a Denso, a 3122 which also has a gap of 0.032

NGK also makes a 5553 which is comparable in everyway, except has a gap of 0.044, which matches the OEM spec. In a Denso, this plug is a 3139 which also has a gap of 0.044.



What do you guys think is the better plug? I ran the NGK 5553 last year with no problems.. Is there any reason why we should go with the smaller gapped plug? Trying to decide which I should order this year.

[toyotafreak]

I've been an Iridium guy (think in 12 years I've replaced twice prior to yesterday). The latest set were still running really nice. After timing belt change checkout run yesterday, I replaced them with new NGK 5553s during oil change and then lit back up. I'm pretty sure it ran better with the Iridium, as measured by the periodic little hickup you can hear when running in gear on the hose. Drivetrain amplifies anything the engine's doing, especially in reverse. I could hear them even in forward though. We'll see if these little micro hickups happen on the water, and if so, I'll switch back to the older Iridiums and report.