Do I have to gap my new spark plugs?

[3hunnazx]

I just changed my spark plugs to NGK IX iridiums. I have a 90 300zx. Do I have to gap them or they fine out the box?
Thanks!

[DCaff300ZX]

You should always check to make sure that the correct gap is set on any new plugs, if for no other reason to be sure you got the right ones if pre-gapped. I know some of the more expensive coated ones are supposed to be sensitive when gapping, but again, being SURE that you have the exact same gap X6 is important.

[3hunnazx]

I literally just put them in as they came in the box, I'd assume their all gapped the same right ?

[NolimitZ32]

Generally all thin tip plugs (platinum and iridium) will come pre-gapped because gapping them could cause you to break the center electrode. As D said however it never hurts to check although I would do that with feeler gauges rather than a gap tool as those are usually a bit more sensitive and have a better finished surface than a gap tool.

[hannman]

I just did my plugs and used the Iridiums. They were not all gapped the same. Some were probably as low as 0.025. I think the manual says 0.044" or around 1mm. I think Ash and SZ suggest to gap plugs to around 0.036" if you're running a decent amount of boost.

[DCaff300ZX]

I just did my plugs and used the Iridiums. They were not all gapped the same. Some were probably as low as 0.025. I think the manual says 0.044" or around 1mm. I think Ash and SZ suggest to gap plugs to around 0.036" if you're running a decent amount of boost.

I found the same with a set I bought, two were definitely tight with the feeler gauge and required a little massaging. I went with .035 IIRC, although my Z guy may have gapped them differently with my build...have to ask him, but I was told by two sources that .035 to .036 is a good range for more than OEM boost.

[NolimitZ32]

0.035 is the right gap. I would be gravely disappointed if I paid $8/plug and they ended up being out of tolerance. Actually I'd be downright pissed.