....Spark Plugs....

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Dave

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I am running the copper core NGK's that I put in on my first plug change and they are doing fine. (the OEM plug) I am going to pull them in the spring and either stay with the NGK's or try the Autolite double platinums depending on my mood at the time. Some others have said they have run the Autolite double platinums with good results in the KJ. I won't run iridiums.

Dave
 

tjkj2002

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Um, I would have to disagree with everything you are stating. Jeep KJ's use "coil on plug" ignition, not waste spark. Iridium alloy spark plugs from Autolite, Champion or NGK (whatever brand you prefer) all have much lower required firing voltage than any brand of copper core plug. They were developed for OE automakers specifically for coil on plug type ignitions. I have personally installed them in over 100 Jeeps with no issue's.
I have installed those type of plugs in many vehicles also and they always come back to have the correct plugs installed,from Jeeps to BMW's,kinda do this crap for a living.

Chrysler engines are designed for copper core plugs(minus the new 5.7's which are junk now anyway).
 

belvedere

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I agree w/ TJ about using copper-core plugs in vehicles that came w/ them OEM. However, I disagree about the 3.7 having a waste-spark ignition system. My Intrepid 3.5, for example, does have a waste-spark system. It has one coil (w/ 2 terminals) per two cylinders. That means that when it fires on the compression stroke (near tdc, of course), it also fires during the exhaust stroke of the other cylinder, thus "wasting" that spark. The 3.7 has a coil on each cylinder, so no need to waste a spark.
 

belvedere

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Motorking, I picked up a set of 985s the other day for my Intrepid, and as I was installing them, I was disappointed to see "Made in China" on the box. How sad for such an iconic American brand. So, I will be looking for "Made in USA" on the next set of plugs I buy. Just to let you know, it does matter to alot of people.
 

tjkj2002

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I agree w/ TJ about using copper-core plugs in vehicles that came w/ them OEM. However, I disagree about the 3.7 having a waste-spark ignition system. My Intrepid 3.5, for example, does have a waste-spark system. It has one coil (w/ 2 terminals) per two cylinders. That means that when it fires on the compression stroke (near tdc, of course), it also fires during the exhaust stroke of the other cylinder, thus "wasting" that spark. The 3.7 has a coil on each cylinder, so no need to waste a spark.
Yeah I have 4.0 I6 on the brain today,had to replace every single gasket and seal on a '01 XJ's 4.0 today but the head gasket.I HATE THAT ENGINE,it never can hold oil for very long,sad part is it only had 20k on it(yes only 20K miles as some older guy owned it and rarely drove it).

But regardless the 3.7 does not like Iridium plugs.


Now my '75 350 Rocket in my old Cutlass loved them but with a MSD ignition(pro billit distributor,6AL box,Blaster 3 coil) and 13.5:1 compression ratio it needed them.


Edit:

For the record the later years of the 3.7,I believe it started in '08 or '09,use a waste spark setup as they only have 3 coil packs on the bank one with plug wires running to bank two.
 
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belvedere

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For the record the later years of the 3.7,I believe it started in '08 or '09,use a waste spark setup as they only have 3 coil packs on the bank one with plug wires running to bank two.

Interesting, I did not know that. I wonder why they made the change?
 

Dmut

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For the record the later years of the 3.7,I believe it started in '08 or '09,use a waste spark setup as they only have 3 coil packs on the bank one with plug wires running to bank two.
I have the parts.pdf for `08 KK, and 3.7l there has 6 sparks and 6 coils

edit: that's weird, in `09 and `10 KK they have 3 coils and cable set. so, you are right. but I still wonder why they've changed it in the middle of production line? they can save like $20 on each car, but is it really worth a change?
 

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Moab

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So I just received my Autolite APP5224's Double Platinum's and they are made in Me-he-co just like the Double Platinum's that I use on My TJ.
I give 'em a try I report back......
 
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Moab

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Another thing,
the Autolite Double Platinums are gapped out of the box at .044 in.:freak3:

But under my hood it says .040in. so that's what I'm going with.:party52:
 

gnp.hiker

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Another thing,
the Autolite Double Platinums are gapped out of the box at .044 in.:freak3:

But under my hood it says .040in. so that's what I'm going with.:party52:

I put the same ones in my '02 recently (@60K) and adjusted the gap to .040. New plugs certainly got our Liberty back to getting better mpg.
 
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