Good point, I will definitely double check with NAPA on Monday.

 

i think you got a manual with a typo-https://www.fordservicecontent.com/Ford_Content/vdirsnet/OwnerManual/Home/Content?variantid=4696&languageCode=en&countryCode =USA&Uid=G1774437&ProcUid=G1790389&userMarket=usa& div=f&vFilteringEnabled=False&buildtype=web

 

That’s a bad link, it doesn’t work

 

I took these from the online manual 2017 F150.



Motorcraft SP520
NGK LTR6BP13 Laser Iridium, or NGK LTR61X-11 Ruthenium HX

The Iridium IX plugs are single rare metal with short life more suited to tuned modified engines. KM

 

sorry about that further searching does show that bigger gap for the NA engines

 

This is the NGK they gave me: ILTR6R8G
91794

 

Per NGK website under fitment, you have the wrong spark plug. That is why the pregap is also wrong. https://www.ngk.com/ngk-91794-iltr6r...ium-spark-plug

 

ILTR6R8G
91794

Is listed for Broncos, none of which have an NA 3.5. The 8 in R8G indicates gap at .8mm or .031 inch. KM

 

That would explain it, glad I didn’t install them yet. Back to NAPA again 🤦‍♂️
The plugs they gave me don’t show up on the napa app either.

 

Returned the wrong plugs today, I ended up with Autolite Ultra Iridium and got them installed this afternoon. The gap on the Autolites was .046” on each plug so I said close enough and in they went. The factory installed Motorcraft Platinum plugs came out with the gaps at .060” after 72k miles.