Spark Plug type

[HawgWagon]

What do you think are the best plugs for a 97 XJ 4.0 5spd.
I know that in my old 5.0 I was told that no matter what the 5.0 motors enjoyed booring old copper plugs more than anything. Any suggestions for the 4.0? and what is the proper gapping?

[ct67_72]

I prefer copper in most things. More so because copper is a better conductor than platinum. It just doesnt last as long. That being said I have platinums in my jeep right now. But Im lazy and dont want to pull the coil pack off too often.
My typical preference goes;
bosch copper
ngk v-power
standard ac-delco
motor craft
bosch platinum
ngk platinum
double platinum.

I do like iridium plugs also, and they would be on the top of my list, but a lot of people wont pay for them.
The densos in my nissan were like 12 or 14$ a plug.

[HawgWagon]

Yeah, I agree with the copper being the best conductor. I have Iridiums in my bike but dont feel like spending that money at the moment. I'll just stick with basic Copper plugs then, you reconmend using bosch copper? and what is the gapping any chance you know off the top of your head?

[ct67_72]

Im not sure on the gap. I like the bosch copper. The real ones that come in the yellow box.

[Hudson]

Yeah, I agree with the copper being the best conductor. I have Iridiums in my bike but dont feel like spending that money at the moment. I'll just stick with basic Copper plugs then, you reconmend using bosch copper? and what is the gapping any chance you know off the top of your head?

.035.

Some guys say .040 is better or even .045 but it eats your plugs up like no tomorrow. I'd personally just gap them at .035.

I just use Champion Copper Pluses. They're like $1.73 a plug.

While you're at it do the cap + rotor + plug wires.

[Pedro]

Jeep 4.0's run best with champion copper plugs, or any copper for that matter. That's what the Internet taught me at least

[CSaddict]

Drop a heat zone and tighten the gap to .028 under boost.