Autolite XP 5245 in an LS7.....
Thread Starter
Joined: Sep 2004
Posts: 3,212
Likes: 1,612
From: Michigan & Florida
Autolite XP 5245 in an LS7..... I have been running Autolite XP5245 plugs in your LS7 for 9 years/50,000 miles. Is anyone else running these in your LS7? I've heard they're one range colder than stock, but IDK for sure. My heads are cut .020", otherwise no other compression increases. I pulled them recently, and found they were all gapped at about .043-.045". I also found #2 cylinder plug had no Iridium on the ground strap, and a .050"+ gap!!! Just a divot where Iridium had once been. They aren't cheap plugs, so when I replace them, I want to be sure I'm buying the proper heat range, though I have no issues with KR or detonation. Thanks, guys....
I have been running Autolite XP5245 plugs in your LS7 for 9 years/50,000 miles. Is anyone else running these in your LS7? I've heard they're one range colder than stock, but IDK for sure. My heads are cut .020", otherwise no other compression increases. I pulled them recently, and found they were all gapped at about .043-.045". I also found #2 cylinder plug had no Iridium on the ground strap, and a .050"+ gap!!! Just a divot where Iridium had once been. They aren't cheap plugs, so when I replace them, I want to be sure I'm buying the proper heat range, though I have no issues with KR or detonation. Thanks, guys....
Autolite seems to be a good match for Ford. Some people think it makes a difference, some not. I've got NGK in 3 of my vehicles and they work great. One thing I learned recently is that some spark plugs have a screw on cap. On a racing application, I'd avoid those as (in my case) over time they can loosen up.
Thread Starter
Joined: Sep 2004
Posts: 3,212
Likes: 1,612
From: Michigan & Florida
Thank you all for responding. No fouling, and only when kinda/sorta lugging the engine (1,800-2,000 rpm half throttle passing in .7 ratio A4 OD) do I get an occasional spark knock, so maybe keep them? @Che70velle Scott, I'm slightly concerned that if I go a range hotter, with as much time as I'm spending in Florida heat, it'll exacerbate any spark knock. Thoughts?
Thank you all for responding. No fouling, and only when kinda/sorta lugging the engine (1,800-2,000 rpm half throttle passing in .7 ratio A4 OD) do I get an occasional spark knock, so maybe keep them? @Che70velle Scott, I'm slightly concerned that if I go a range hotter, with as much time as I'm spending in Florida heat, it'll exacerbate any spark knock. Thoughts?
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Thread Starter
Joined: Sep 2004
Posts: 3,212
Likes: 1,612
From: Michigan & Florida
Mike, I don’t think that a hotter plug will affect pre-ignition. The hotter plug is really only to “self clean” itself better than the colder plug. It will increase cylinder temps some, but it sounds like you might should pull a degree or two of timing out of that area where it’s pinging. I’ve seen this happen to many cars in that range, including my own stuff, and pulling a couple of degrees out in that area where it lugs, always works to smooth things out.
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