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Unread 05-24-2013, 04:19 AM   #1
NH2112
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Which spark plugs?

I'm finally putting my 4.2l back together, and am looking for the best spark plugs to use. It's got a 4.0l head, it's been Nuttered, and has the large Ford cap & rotor. It had Bosch Platinum FR9HP, but I'd like to make sure I'm getting the hottest spark my ignition system is capable of producing. Are the Bosch good to stay with, should I use the Denso APP985s like my 2000 TJ took, or something else? Thanks.

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Unread 05-24-2013, 10:33 AM   #2
jsd1991yj
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Im running these e3 spark plugs in my 1991 2.5. I dont have any complaints. I am also running the DUI ignition. http://www.e3sparkplugs.com/
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Unread 05-24-2013, 10:35 AM   #3
Siva283
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My 95 likes Champian Copper Core. I put bosch platnums in it once because I used them with great results in every other car I have owned but my Jeep absolutly hated them
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1995 YJ. 2 inch BDS Spring lift. 1 inch shackle lift. 1.25 inch JKS Body Lift 33x12.5x15's. Engo 10,000 pound winch.

[QUOTE=Magnum;14117863] I gave the Jeep the required offering of $$, sweat, and blood, and everything works fine now. -- Jim[/QUOTE]

[QUOTE=ldso;16498409]. It started with a $200 axle, and a few thousand dollars later I was done :)[/QUOTE]

[QUOTE=Luuca;16122017]diagnose the real issue before you start going all Obama on it - spending mad cash you'll need for other important things.

Ask me how I know...[/QUOTE]

[QUOTE=Overhead;17658665]this is also my second set of RC springs this year. I'd rather spend the money again and get something that will last.[/QUOTE]
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Unread 05-24-2013, 02:22 PM   #4
kahanabob
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Quote:
Originally Posted by jsd1991yj View Post
Im running these e3 spark plugs in my 1991 2.5. I dont have any complaints. I am also running the DUI ignition. http://www.e3sparkplugs.com/
I also run E3's.............likewise, no complaints
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Unread 05-24-2013, 03:26 PM   #5
JBTJ
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Quote:
Originally Posted by NH2112 View Post
I'm finally putting my 4.2l back together, and am looking for the best spark plugs to use. It's got a 4.0l head, it's been Nuttered, and has the large Ford cap & rotor. It had Bosch Platinum FR9HP, but I'd like to make sure I'm getting the hottest spark my ignition system is capable of producing. Are the Bosch good to stay with, should I use the Denso APP985s like my 2000 TJ took, or something else? Thanks.
I like the Autolite Iridium plugs should last about 200k.
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Unread 05-24-2013, 03:28 PM   #6
PA_YJ19
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Quote:
Originally Posted by Siva283
My 95 likes Champian Copper Core. I put bosch platnums in it once because I used them with great results in every other car I have owned but my Jeep absolutly hated them
X2 on the champion truck plugs, that's what our 4.0 was made to use an it really likes them. Mine came with Bosch plat 4 or sum crap and switched to the plain old copper champion truck plugs and haven't had an issue since, don't waist it ur money on the expensive ones. All it needs is a spark, our jeep motors don't need ne fancy 3 or 4 pronger to do the trick.
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Unread 05-24-2013, 03:55 PM   #7
dancytron
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Consensus is the best thing to run are regular old fashioned copper core plugs like the service manual says.
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Unread 05-24-2013, 05:59 PM   #8
JBTJ
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Quote:
Originally Posted by dancytron View Post
Consensus is the best thing to run are regular old fashioned copper core plugs like the service manual says.
True, if you like to replace the plugs every 20k. If not, use a better plug. Nothing wrong with that.
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Unread 05-24-2013, 06:08 PM   #9
Siva283
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Quote:
Originally Posted by JBTJ View Post

True, if you like to replace the plugs every 20k. If not, use a better plug. Nothing wrong with that.
My gas milage and power drop when I use anything other than copper core. I got almost 50, 000 on mine and they still look new. I habe been throigh a few cap and rotors though and a set of wires. Proper maintenence to keep the engine in good shape will make them last awhile

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1995 YJ. 2 inch BDS Spring lift. 1 inch shackle lift. 1.25 inch JKS Body Lift 33x12.5x15's. Engo 10,000 pound winch.

[QUOTE=Magnum;14117863] I gave the Jeep the required offering of $$, sweat, and blood, and everything works fine now. -- Jim[/QUOTE]

[QUOTE=ldso;16498409]. It started with a $200 axle, and a few thousand dollars later I was done :)[/QUOTE]

[QUOTE=Luuca;16122017]diagnose the real issue before you start going all Obama on it - spending mad cash you'll need for other important things.

Ask me how I know...[/QUOTE]

[QUOTE=Overhead;17658665]this is also my second set of RC springs this year. I'd rather spend the money again and get something that will last.[/QUOTE]
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Unread 05-24-2013, 06:27 PM   #10
NH2112
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Quote:
Originally Posted by JBTJ

I like the Autolite Iridium plugs should last about 200k.
Oh, I'm gonna have a diesel in it LONG before I hit 200K.

I guess the nice thing is spark plugs are inexpensive so if the ones I choose don't work, it's no more than $25 and 15 minutes to try something else.
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Unread 10-24-2013, 05:40 PM   #11
supersport126
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I'm running a 258 with clearwater 4.0 head and I was running Champion rc-9yc4 because thats what the "Tim Weaver" article called for. Those are now hard to find and Autolite 3923 is a replacement I'm currently running. My question is everytime I look at a stock 4.0 plug the electrode is quite a bit longer then what I have and I'm afraid The piston is gonna hit it. What's the best current plug for a "built" 258/4.0 head?
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Unread 10-30-2013, 12:44 PM   #12
jasonjones21
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Bosh platinum +4
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Unread 10-30-2013, 12:59 PM   #13
Tom95YJ
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Champion Coopers, Ive tried a bunch of other plugs in Various different Jeeps and I've come to the conclusion Jeeps do not like anything other then the plain jane Champions.
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Unread 10-30-2013, 01:51 PM   #14
Siva283
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Quote:
Originally Posted by Tom95YJ View Post
Champion Coopers, Ive tried a bunch of other plugs in Various different Jeeps and I've come to the conclusion Jeeps do not like anything other then the plain jane Champions.
Quoted for truth
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1995 YJ. 2 inch BDS Spring lift. 1 inch shackle lift. 1.25 inch JKS Body Lift 33x12.5x15's. Engo 10,000 pound winch.

[QUOTE=Magnum;14117863] I gave the Jeep the required offering of $$, sweat, and blood, and everything works fine now. -- Jim[/QUOTE]

[QUOTE=ldso;16498409]. It started with a $200 axle, and a few thousand dollars later I was done :)[/QUOTE]

[QUOTE=Luuca;16122017]diagnose the real issue before you start going all Obama on it - spending mad cash you'll need for other important things.

Ask me how I know...[/QUOTE]

[QUOTE=Overhead;17658665]this is also my second set of RC springs this year. I'd rather spend the money again and get something that will last.[/QUOTE]
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Unread 10-30-2013, 02:07 PM   #15
bpounds
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When I got this Wrangler, first thing I did was take it to my mechanic and ask him to rebuild the carburetor and generally give it a look over. He said fine, but only if you let me replace those plugs with Champion. I forget what it had in it already. But this guy has been around the 4.2L for a long time.
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