Proper way to gap iridium plugs?

[Whimsey]

I used NGK Iridium IX plugs in 1996 2.0 Zetec Contour per Rock Auto specking them for my engine. They came pre gapped at ~.043 but the gap spec for the engine is ~.054. I re gapped them to the .054 and they run great. I don't know why RA recommended these plugs as I have a waste spark ignition so they'll likely wear out a lot sooner. But since they are super easy to change being a 4 cyl without an engine cover and not coil-on-plug I can change them in ~15 minutes

. Do Iridium plugs operate properly with a narrower gap than say platinum plugs for the same engine?

Whimsey

 

[Snagglefoot]

Originally Posted by Whimsey
I used NGK Iridium IX plugs in 1996 2.0 Zetec Contour per Rock Auto specking them for my engine. They came pre gapped at ~.043 but the gap spec for the engine is ~.054. I re gapped them to the .054 and they run great. I don't know why RA recommended these plugs as I have a waste spark ignition so they'll likely wear out a lot sooner. But since they are super easy to change being a 4 cyl without an engine cover and not coil-on-plug I can change them in ~15 minutes

. Do Iridium plugs operate properly with a narrower gap than say platinum plugs for the same engine?

Whimsey



Your 0.054 gap for your 1996 car was not for Iridium plugs, but it shows the ability of Iridium plugs to function at the wider gaps they will have at the end of their life. Next time, leave them alone at their factory gap of 0.043.

 

[StevieC]

The guy in the video is using the wheel gapper incorrectly. It looks at though he is trying to force a bigger gap by sliding it further up the wheel. That's not how it's supposed to be used. The hole in these wheel gappers is for opening the gap up and the wheel section is for checking that you opened it to the correct gap. Most people think the hole is so they can put it on their keys.

 

[Panos]

Originally Posted by Imp4
The proper way to gap them is to not gap them.

They will be good out of the box.

I re-gapped my currently installed NGK Iridium IX sparkplugs twice, closing the gap (original gap was 1,1mm) that have grown bigger while the were wearing (after about 55.000kms then after another 40.000kms).Both times ,the gap was over 1,3mm and after gapping the low-end rev response was noticeably improved.The factory spec interval (with standar plugs) is 60.000kms.I am aiming for 120.000+kms.

 

[Whimsey]

Originally Posted by Snagglefoot
Originally Posted by Whimsey
I used NGK Iridium IX plugs in 1996 2.0 Zetec Contour per Rock Auto specking them for my engine. They came pre gapped at ~.043 but the gap spec for the engine is ~.054. I re gapped them to the .054 and they run great. I don't know why RA recommended these plugs as I have a waste spark ignition so they'll likely wear out a lot sooner. But since they are super easy to change being a 4 cyl without an engine cover and not coil-on-plug I can change them in ~15 minutes

. Do Iridium plugs operate properly with a narrower gap than say platinum plugs for the same engine?

Whimsey



Your 0.054 gap for your 1996 car was not for Iridium plugs, but it shows the ability of Iridium plugs to function at the wider gaps they will have at the end of their life. Next time, leave them alone at their factory gap of 0.043.

Thanks, I was wondering about that. I can easily remove them and re gap them to the NGK factory setting of .043. The 2.3 Ecoboost in our Explorer comes with iridium plugs made by NGK for Ford I believe. The Ford recommended gap on those is .027. I ordered replacement Motorcraft plugs and they came correctly gapped at .027-.028.

Whimsey

 

[bbhero]

Originally Posted by hallstevenson
Originally Posted by Snagglefoot
Well let's check. I see gaps at 0.040 to 0.044 inches for Iridiums. What other gaps are your owners manuals recommending for Iridium plugs? Not Platinums and certainly not Coppers.

'08 G35 with the VQ35HR engine and the FSM calls for Iridium plugs gapped at 0.043". The plug Nissan/Infiniti specs is FXE22HR11 and DENSO pre-gaps these at 0.044".



^^^^^

Exactly right. FXE plug is what was in Nissan Altima VQ before the latest change... And the Denso iridium TT plugs I have in in now have a 0.040 gap.

 

[ka9mnx]

Originally Posted by Whimsey
I used NGK Iridium IX plugs in 1996 2.0 Zetec Contour per Rock Auto specking them for my engine. They came pre gapped at ~.043 but the gap spec for the engine is ~.054. I re gapped them to the .054 and they run great. I don't know why RA recommended these plugs as I have a waste spark ignition so they'll likely wear out a lot sooner. But since they are super easy to change being a 4 cyl without an engine cover and not coil-on-plug I can change them in ~15 minutes

. Do Iridium plugs operate properly with a narrower gap than say platinum plugs for the same engine?

Whimsey

Gapping was more about the old copper plugs, high compression and getting them to fire correctly. Just install them out of the box. You will not have a problem with waste spark wear (that's where platinum's originated from). My Denso Iridium's have a platinum plug on the ground electrode to ensure this is not a problem (don't know about NGK's) Only problems with waste spark wear is when trying to use old copper plugs (don't ask me how I know!).

 

[StevieC]

ka9mnx, having just replaced the plugs in my Caravan (long story), I gapped each plug before I put them in. I found every plug to be inconsistent with the next one with upto 0.020 of a difference and they were supposed to be "pre-gapped" plugs and came with the cardboard cylinder over the threads to keep the cap from changing in shipping.

For what it takes you might as well check the gap before putting them in. It's not hard, it doesn't take a lot of time so why not do it anyway? Seems silly not to.

 

[Snagglefoot]

Originally Posted by StevieC
ka9mnx, having just replaced the plugs in my Caravan (long story), I gapped each plug before I put them in. I found every plug to be inconsistent with the next one with upto 0.20 of a difference and they were supposed to be "pre-gapped" plugs and came with the cardboard cylinder over the threads to keep the cap from changing in shipping.

For what it takes you might as well check the gap before putting them in. It's not hard, it doesn't take a lot of time so why not do it anyway? Seems silly not to.


Stevie, you mean 0.002, correct? Normal gaps are 0.040 to 0.044.

 

[StevieC]

No I mean I found plugs gapped between 0.020 to 0.040, I missed a 0 in my number above. I needed mine to be 0.044 for my application so naturally I had to open the 0.040 a smidge but the 0.020 I'm glad I found because it would have been out pretty far from spec on supposedly pre-gapped plugs and these plugs are rated to last 100,000 miles in this Chrysler application and aren't easy to get at with needing to remove the plennum and a bunch of other crap so to take two minutes and gap them makes sense.

 

[Snagglefoot]

Originally Posted by StevieC
No I mean I found plugs gapped between 0.020 to 0.040, I missed a 0 in my number above. I needed mine to be 0.044 for my application so naturally I had to open the 0.040 a smidge but the 0.020 I'm glad I found because it would have been out pretty far from spec on supposedly pre-gapped plugs and these plugs are rated to last 100,000 miles in this Chrysler application and aren't easy to get at with needing to remove the plennum and a bunch of other crap so to take two minutes and gap them makes sense.


Agreed. The 0.02 is a large difference.

 

[demarpaint]

I check them just in case the box was dropped and the gap is off. If it is off I return the plug, as damaged goods.

 

[ka9mnx]

Originally Posted by StevieC
ka9mnx, having just replaced the plugs in my Caravan (long story), I gapped each plug before I put them in. I found every plug to be inconsistent with the next one with upto 0.020 of a difference and they were supposed to be "pre-gapped" plugs and came with the cardboard cylinder over the threads to keep the cap from changing in shipping.

For what it takes you might as well check the gap before putting them in. It's not hard, it doesn't take a lot of time so why not do it anyway? Seems silly not to.

Wow! I have never seen plugs come out of the box with that spread. Denso says not to gap their plugs because you could damage them. If you've seen their fine wire center electrode (.040") I'd be afraid to put anything near it.

 

[DGXR]

If new plugs must be gapped, you could do it as shown in the video. Personally, I would avoid banging a new plug that way. With iridium or platinum plugs, avoid touching the hot (center) electrode too much when adjusting the gap. All of the adjustment should be done by bending the ground (strap) electrode. Do not increase the gap by prying against the center electrode. Iridium and platinum are very hard metals which makes them very brittle... they could chip or crack.