rb66

Hi, i'm new here. i've been researching a spark plug change on my 2011 f150 eb. been reading a lot here and 534s are the way to go but it says right on the box of the plug that they are not adjustable. so, how is everyone here adjusting theirs. i have not seen any mention of not being able to adjust the gap. one guy said you can do it, very carefully. so, what to do? i never trusted the factory gap. i always gapped my own plugs, regardless. but i never had iridium tipped. i have a stocker that runs great. just hit 52k and want to change the plugs only because ford decided on a new/better? plug. thanks in advance for any help.

Roughneck12

crystalsource

1-17-2020. I cannot find the sp534 anywhere. Got tips? Next best substitute plug?

kcooper99

Just bought them on Rockauto

wchain

sp580

Reflections Detail

I have a 2012 3.5 EB. Was time to replace the plugs, pulled the old ones (sp534) and bought new sp580 gapped them at .028 (I have a full race tune) and things sounded better and seem to smooth out.

Went on a long road trip and my miles/gallon dropped a lot. I use to get 15-17mph at 80mph and now its 13.5-14mph at 80mph.

Is this spark plug related in your opinion?

Cheers

dsg2003mach1

you might be better served to start a new thread but from what I've read plug gap can hurt mileage if it's too tight. You basically want the biggest gap possible that doesn't result in spark blow out. Your tuner should be able to verify desired plug gap for your combo. I'm kind of surprised to see that much drop though