Spark Plug Gap: NGK Iridium

[markreda]

I just picked up a set of NGK Iridium spark plugs.
The gap on the stock plug BKR6EIX is 0.030

What is the correct gap on the BKR7EIX (1 step colder)?
I'd like to check the gap before installing them

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[drees]

Same gap. You could go 0.028 if it misfires under high rpm and load.

[markreda]

I did a little searching on NGKSparkPlugs.com and I believe the BKR7EIX come pre-gapped to 0.025 (based on a 1994 AUDI S4 2.2 Turbo which use the same plug)

I guess I'll just gap them to 0.028

[drees]

0.025 should be OK, too.

[vinceGC8]

does having a smaller gap have a negative effect on its performance or cause any risk to anything?

[sixpack subaru]

Originally Posted by linkzard

does having a smaller gap have a negative effect on its performance or cause any risk to anything?

Hey Bud,
Under extreme load/boost a smaller plug gap is mandatory. The reason for this is the higher the pressure, the more voltage required to jump the gap. (That's why there's always more lightening waay up in the sky than there is down here! ). Also, the leaner the mix, the harder it is for the spark to jump the gap, (more Volts Required). Normally the electrons use the molecules of fuel as a conductor, lowering the resistance and therfore the required voltage to get the 'spark' across the primary and ground electrodes. Anyway, if you gap them TOO small, then there is insufficient 'spark face', (basically there is not enough 'match' to light the fuel). So, in short, that is why FHI have spent the money and time finding out that 0.8mm, (sorry about the metric ), was the optimum for both, (for std conditions). I have run 0.7mm for years in modified EJ series Engines of all descriptions without issue.

Hope this helps,

Sixpack Subaru