Hi guys,

I'm changing my plugs for my car and forgot what's the gap for the plugs and torque to tighten. My car is supercharged w/Vortech and I'm using NGK 7173.

Thanks,
John

 

FI spark plug gap should be between .030 and .035. the bigger, the less boost. like 17 psi you might go down to .030, if more boost, you need to close up the gap even more, but you'll be needing a spark system, additional ignition module, etc.

With mild boost, 7-10 psi, you'll be ok with, say, .33.

In principle, the more boost, the denser the air/fuel mixture inside the cyl, therefore, the harder for the spark to jump the gap. So you close up the gap.

In idle, though, the smaller gap will possibly hurt, since the mix is not that thick.

I just hand-tighten the spark plugs. And then just re-check after a couple of heatcycles.

 

the torque spec for spark plugs is 18lbs/ft. I don't know if that = hand tight or not.. it's pretty easy to just throw a torque wrench on each one for two seconds to be sure.