spark plug
King Hater
Joined: Dec 2013
Posts: 6,973
Likes: 874
From: MONTANA
So I got bored and decided to try the Sp542's. I gapped them at .025 like the guys in raptor forum suggested. When I first started the truck I could tell a difference at startup. The truck seemed to idle a little steadier. I also didn't notice the idle bump in the seat as much. Driving it seemed to be more responsive. I ran it about 20 miles mixed interstate and in town. Initial thoughts are I like the change. I will continue to drive it and I will report back.....
Senior Member
Joined: Jul 2015
Posts: 10,934
Likes: 2,457
From: Minneapolis
Okay. Question on gapping
I picked up 6 SP534 and they were all gapped at .030 out of the box. From the various threads I read, I was expecting the gapping to be all over the place.
Or is the poor gapping in the original set installed from the factory?
I will be measuring the gap as I pull each original plug for curiosity.
Thanks
I picked up 6 SP534 and they were all gapped at .030 out of the box. From the various threads I read, I was expecting the gapping to be all over the place.
Or is the poor gapping in the original set installed from the factory?
I will be measuring the gap as I pull each original plug for curiosity.
Thanks
There shouldn't be variety with new in box plugs, but there is some as you can see from comments. I believe I had to adjust 2 of 8 when I did mine. The plugs for the V8s are the same as yours (as far as I can tell), just gapped larger. Used to be sp519, now sp548.
5 Year Member
Joined: Apr 2017
Posts: 5,053
Likes: 1,631
From: Arizona
Yes to both questions, unless you have a tune, then I'd suggest gapping around .028. Also it isn't .30, it is .030 Please do not gap to .30.
Although tothemax seems to had really good success with the sp542's gapped to .025 with a tune...I am tempted to go that route next time.
Although tothemax seems to had really good success with the sp542's gapped to .025 with a tune...I am tempted to go that route next time.