Gapping iridium plugs

[Cumsterdump]

i picked up some autolite xp985s for my coil on plug 4.0 but none of the forums i read gave a definitive answer about if they should be gapped, how much, and the right tool to do it.

appreciate any tips or clarification

 

[macleanflood]

0.035...might be a bigger gap on the 05-06.

Lots of tools to measure. Round disc with a ramp is what I use.

-Mac

 

[rob@fain]

These should be pre gapped. Iridium plugs have a smaller electrode that is very fragile.

 

[rob@fain]

0.035...might be a bigger gap on the 05-06.

Lots of tools to measure. Round disc with a ramp is what I use.

-Mac

I wouldn't use the round disk to gap, those pewter gapping tools leave a residue that can cause the plug to foul.

 

[macleanflood]

 

[k1n3k]

These should be pre gapped. Iridium plugs have a smaller electrode that is very fragile.

This. Don't gap Iridium plugs. If you drop one and bend the ground strap, replace it as well.

 

[Chippy]

I’ve always gapped them to spec and just put the XP985 plugs in my 2005 4.0 this past weekend. Gapped them to .035 with a wire gap tool. They came with a way too small gap of .025.

Just be careful with them and you’ll be fine. My old turbo ST used to EAT plugs every 15k miles and the gap would widen significantly in that timeframe. Always replaced them with iridium and I have never heard they shouldn’t be gapped until I joined this forum lol. Any tuner would tell you to gap them

 

[BlueC]

Round disc with a ramp is what I use.

Not with iridium plugs, that will destroy it. You need to use the wire tool. You hook that little notched blade on the strap and pull/leverage into position if needed.

Also, if new, check them but most are pre-gapped correctly.

 

[Cumsterdump]

0.035...might be a bigger gap on the 05-06.

Lots of tools to measure. Round disc with a ramp is what I use.

-Mac

round disc doesn’t work with these types of plugs. extremely fragile.

 

[Cumsterdump]

I’ve always gapped them to spec and just put the XP985 plugs in my 2005 4.0 this past weekend. Gapped them to .035 with a wire gap tool. They came with a way too small gap of .025.

Just be careful with them and you’ll be fine. My old turbo ST used to EAT plugs every 15k miles and the gap would widen significantly in that timeframe. Always replaced them with iridium and I have never heard they shouldn’t be gapped until I joined this forum lol. Any tuner would tell you to gap them

that’s what i thought. when i did iridium in my ecoboost they needed gapped.

 

[Siwash89]

Gapped mine with the disk wire tool

 

[Christian.mers]

Gapped mine with my fingers and eyes

 

[Chippy]

that’s what i thought. when i did iridium in my ecoboost they needed gapped.

Yeah. I used to tune them too and the ecoboost is really sensitive to what plugs/proper gap. I’d always do one step colder with a slightly more narrow gap because it would widen pretty quick if you pushed over 400whp. People in the ecoboost space were basically taught to never trust the pre-gapped plugs.

The 4.0 makes so little power and is a tractor like N/A motor so I’m sure it doesn’t really matter if the gap is a little off, but old habits die hard and I check the gap every time regardless.

 

[Zorba]

Mine were gapped way under - spec is .35, but I went with .40 as that 2006 ignition is so hot that it was firing fine with the old plugs at .63. Don't forget to put never-seeze on the threads. (Cue flamewar about never-seeze on plug threads)

 

[BlueC]

spec is .35, but I went with .40 as that 2006 ignition is so hot that it was firing fine with the old plugs at .63.

Hot ignition and relatively low cylinder pressures can run those larger gaps. In theory, the larger gap, up to a point obviously, will promote a more complete burn.

 

[Zorba]

Hot ignition and relatively low cylinder pressures can run those larger gaps. In theory, the larger gap, up to a point obviously, will promote a more complete burn.

That was my thought.

 

[hear]

Доверяй, но проверяй

grad school Russian pays off yet again.

 

[TheBoogieman]

I wouldn't use the round disk to gap, those pewter gapping tools leave a residue that can cause the plug to foul.

Now you tell me. I used the disk on the iridium plugs I installed 8 years ago. Maybe I should go check them.

 

[Link]

This. Don't gap Iridium plugs. If you drop one and bend the ground strap, replace it as well.

No. Just no

 

[Link]

I wouldn't use the round disk to gap, those pewter gapping tools leave a residue that can cause the plug to foul.

No it doesn’t hurt a thing.