Do IRIDIUM plugs need a larger GAP than Platinum, .050 vs .044??

[fixizin]

I notice that every variation of Platinum spark plug that is even remotely spec'd for our Ranger/Vulcans comes pre-gapped to the correct "plate" value of 0.044"... just splurged for some Autolite (Fram?) Iridium XP103s, and they come with a gaping-yuuuge-gap of .050...

... should I install them AS-IS, or pinch them down a hair to .044??? Thanks in advance.

(5 of my 6 plugs have been in there since she rolled off The Twin Cities line in Jan. 1999!... hey, only 83k total miles... lol... what do you think the gap will be on the originals when I pull them???)

 

[rubydist]

In my opinion, iridium plugs can have a larger gap than standard or platinum plugs because the small point on the electrode concentrates or focuses where the spark will jump, whereas the flat areas of the regular plug results in the spark originating in a different spot at different times. Also, a sharp edge facilitates the spark jumping, and the regular plugs will round off faster than the iridium ones do. So, imho, you are fine to install them at .050" but it would not hurt to close them a bit. Be very careful if you close them up, because the iridium is very brittle and easy to break off!

 

[19Walt93]

I would set them to spec, in fact, I check every plug gap because "pregapped" plugs can have been dropped during shipment. The gap is decided by the amount of spark, compression, and engine load.

 

[Eddo Rogue]

Id check em the gaps, and gap em to what the plug calls for. Ford specs is for the original plugs.

 

[fixizin]

Id check em the gaps, and gap em to what the plug calls for. Ford specs is for the original plugs.

Err, umm, NOT following you... don't think plugs call for any particular gap, they just come pre-gapped to the most common end-use engine... yes/no?...

 

[franklin2]

Always check the gap, like was mentioned it can close up just from shipping.

It's common knowledge that you can get a hotter spark if you open the gap up. But there is a trade off. The factory specs the gap with power and plug life balanced out. If you want to open the gap, then you will need to change the plugs more often. The new fangled precious metal plugs will last longer, but when they do wear, they will start miss-firing sooner with a wider gap. And with a wider gap your wires and the rest of the ignition system needs to be in good condition.

If you do not mind changing the plugs more often, you can experiment with widening the gap some.

 

[rubydist]

Except that iridium plugs will last 4x longer than standard or platinum plugs, so there is zero risk of having to change the iridium plugs sooner than platinums even if the gap is a little larger to start with, for reasons I described in my earlier post.

 

[19Walt93]

If the spec is .044 and you go to .050 it shouldn't hurt anything, a drastic increase in gap will increase the odds of a misfire and stress the ignition coil and/or module. We often saw people go way beyond the recommended 100k on the original plugs, the gaps were huge and the coil-on-plugs were dead.

 

[Eddo Rogue]

Oh m

Err, umm, NOT following you... don't think plugs call for any particular gap, they just come pre-gapped to the most common end-use engine... yes/no?...

IME the computer at the parts counter specifies the gaps, the parts guy just most likely won't mention it.

I had to ask the to turn the screen a little towards me and loan me a pen so I could write the gap down on one of the spark plug packages.

Yes they are pre gapped leaving the factory, but then its a long bumpy ride to you.

Mine were all within spec except one was a little small, probably took a whacking during shipping.
It's easy to check them before installing.

 

[pjtoledo]

after reviewing the tech notes & FAQs on Denso and Bosch they don't recommend larger Iridium gaps.
Denso has a note where their "U" gap ground strap actually creates a larger flame kernel at the spec'd gap.

 

[Eddo Rogue]

I dont mess with the ones that have a funky shaped ground ends, just the regular L shape. Also super careful/gentle if it has a tiny electrode.