BEST PLUGS for a stock 4.0 OHV...?

[Delta_1980]

type "laser plugs" in the search bar. they don't seem too far off.

 

[FarmageddonNRO]

I have NGK Iridiums in my 91 XL and I have to say that they have easily been the best plug I have used to date. You don't always get what you pay for, but these suckers are solid plugs, sold!

 

[malohnes]

I have had NGK Iridiums for almost 3 years now and they foul-up and need cleaning just as frequently as the NGK Plats. I have noticed perhaps a bit less crud when I do clean them, which is every six months or so. The tips are never bad, but the outside electrode is usually crusty.

I have noticed far more differences in plug wires. NGK wires have been the best since they seem to hold the plug and last a season or so longer. Recently switched to DUI Live wires and really them, but no time to speak of to determine if they are any "better". Autolite, Dura-last, and Napa's house brand all have been crap...falling apart - boot separating from wire and scorching. The Autolites seemed to have the best wow factor after switching, but then pinging missing came back like before.

FWIW, I have had head issues on my truck - 2 cracked heads on the driver side bank. My LIM bolts like to loosen up, so before and after winter, I give everything a quick clean, and snug job and all is well.

After cleaning the plugs, I fire up the Eploder, bring it up to normal operating temp and run a mason jar of water in a vacuum port off the intake tree while revving to about 2000rpm's. Seems to work well cleaning the o2 sensor and cat. Noticeably improves performance and really smooths out the idle.

 

[malohnes]

A quick addendum to the Livewires and Sceamin Demon coil pack. After a 250 mile trip I can say that the coil and wires definitely run smoother and slightly hotter than the NGK wires I have most recently used with the stock coil. I also ran a test to see how much difference there was visually when firing a stock copper Autolite and the NGK Iridium. The Autolites put out a brighter spark by far.

Not sure if this translates into better performance, but I am certain they won't last as long as the Iridiums. I'd rather have the performance over longevity, particularly when it is easy and quick to swap plugs.

Also wanted to mention that I have been impressed by the quality of the Livewires and Screamin Demon Coil Pack. Time will tell if they last, but so far so good!

 

[malohnes]

Update - NGK Iridiums still work great, but switched to Extreme Spark Torque Master Star series. While the Autolites were fine, the Extreme Spark are quite amazing in that even with heavy depositing from head issues, the pinging is FAR less than when I had the Autolites. They seem to handle the spark much better when fouled and deposited with carbon and oil really cam alive when I used the Livewires and Screamin Demon coil pack. I was not prepared for such a noticeable difference, but there it was. They were great to work with, quick in handling the order and always responded to phone or email contact.

My truck is down getting 95tm heads with fresh valve gear replacing old, worn and cracked heads and valvetrain. JBA headers and Magnaflow cats will round out the package. Then I'll get to see what that will do for the truck. So far, very impressed with Extreme Spark.