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That is the set that I used, NGK plugs made for the Hemi.
The owners manual states a gap of 0.043", I had to adjust the NGK plugs as they were all around 0.041". I used a set off feeler gages to check and set the gap.

I know many would rather use the Iridium plugs as they are good for 100,000 miles and are now listed by Mopar. I don't mind changing the plugs every 30K miles, especially being as easy as they are to change.

I would like to learn more about the ignition system and maybe upgrading the coil packs. There has to more that can be pulled from these great engines, especially considering that the Rams are stock at 390HP and the Jeeps are at 360HP, why the difference? Just in the Tuning?

Sorry, not trying to highjack a thread, I will also search the forum to see what I can find.
The jeeps and rams use different intake manifolds. The rams have an active runner valve within the manifold that allows for more torque. This is mainly for the fact that it's a truck and is expected to haul/tow. The exhuast and tuning is also a bit different as well. If you want that extra power it's very easy to obtain with a little money. Intake/exhaust/93tune adds over 50 hp and 60 tq. Depending on parts the increase can be even greater.
 

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2005 Jeep Grand Cherokee 5.7 Hemi
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5.7 V8 Hemi (2011-2013)
Mopar p/n 05149177AB (NGK Yttrium ZFR5C-11)
(.043 gap, 16 plugs, tighten to 18.5 - 22 ft. lbs.)

5.7 V8 Hemi (2014-2015)
Mopar p/n SP143877AA (NGK Iridium 1LZFR5E-11)
(.044 gap, 16 plugs, tighten to 18.5 - 22 ft. lbs.)
What about 2005 Jeep Grand Cherokee 5.7 hemi?
 

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JGC
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205 Posts
@TheMadcat Thanks for the advice of the swivel magnetic spark plug extension. Did not have one of those. Got the plugs a few weeks ago but have not installed yet, no hurry as only 91k miles, but will get to it this spring. Ordered the gearwrench one from Amazon.
 

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Pretty glad I found that. I had started with a standard extension and spark plug socket, with the rubber thingy on the inside. Pulled the first plug and when I pulled the plug out of the socket the rubber thingy came with it. That's a problem, if it comes off when I put the plug back in it will be a pita to get back out. So, tried a different socket I had in the toolbox and this time, pulled the plug out of the socket, and the extension came off. Same problem really, if that happens while installing the plug.... This tool seems like it was made for the hemi, highly recommend.
 

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JGC
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205 Posts
Replaced the plugs today. Went with the stock NGK Laser Iridiums from Rock Auto. I now understand why you need the 5/8 Magnetic Swivel Spark Plug Socket with Extension. My Gearwrench socket (from Amazon) worked perfect. Without it, it would have been a PITA. With 8 dual coil packs (10mm bolts) and 16 plugs, along with dielectric grease and anti-sieze, it takes awhile. With the right magnetic swivel socket, the difficulty is a 2 out of 10. On the passenger side all the coil pack connectors clicked off easily. On the drivers side, the back three didn't want to come off, and, luckily, discovered quickly the wiring was long enough that you don't need to pull the connectors off to pull out the coils.
Anyone buying plugs, brake pads, etc. from Rock Auto, this shareable, multi-use, 5% discount code is good through 3/29/2020 ... 129130783120234507
 

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Grand Cherokee
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I also went with NGK Laser Iridium in my 2011 Hemi that is recommended for the NGK copper plugs. Runs exactly the same.
 

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2014 Jeep Grand Cherokee Summit 5.7L
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Anyone used, considering using, or discussed using the NGK Ruthenium HX?
Just picked up a set form R.A.#96355, seemed to be a decent price, comparable to Iridium.
Won't have any feedback until I can get across the border again for a set of Coil Packs.
Opinions?
 

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Grand Cherokee
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Like everyone says, other than OEM plugs "can" cause problems... ...some people have gone with other brands or models of plugs and had problems.... ....people don't check the gap on plugs anymore, since many come pre-gapped.... ....but if you buy a different brand or model, how do you know they are gapped properly? If they are gapped incorrectly, that would cause problems.... ...also DIS ignition system work on different schema, some sharing a coil between plugs, the Hemi has has shared coils, this means some plug types, like single platinum, will erode faster because half the plugs have a reverse current flow.....

What "Seems" to be true, OEM Plugs for different M/Y work just as fine in other M/Y.... ...i.e. FCA simply switched suppliers, or went with longer life plugs, didn't make any change in the engine that required different plugs.... ....folks have no problem using the Champion plugs that were recommended for earlier HEMI's, I and others have no problem using the NGK Laser Iridium recommended for later HEMI's....

Why do you need a set of Coil Packs? You realize, unless you've done a ton of mods that has significantly increased the density of the A/F charge in the cylinder or raised top RPM a lot, higher performance or new coil packs are provide absolutely no change in power.....
 

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2014 Jeep Grand Cherokee Summit 5.7L
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While I will be the first to honor my inexperience with Hemi engines, I do trust the many years of experience of my butt Dyno. And one of the first dollar for result bolt on upgrades I prefer to spend a few bucks on is to upgrade ignition parts where possible. I have personally felt the difference of a quality performance upgrade of new coils, and that's across everything from 4 cylinder, V6's to 'other' V8's. Its not always about the power, but sometimes its about the performance change, the reactivity and efficiencies. Even if its just a twinge better... better is better. Also, I always gap my plugs, who would ever trust the quality control of mass manufacturing. Its just a tiny process that we all do... no?
 

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2014 Summit 5.7 4wd 20" tires swapped to 18", added all skid plates
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I'm skeptical of claims of increased power from coil replacement. But... here is link to someone doing dyno runs. As I read it they changed nothing but the coils and did the testing back to back. They did two different vehicles, one got a big increase in power, the other a small increase.

 

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Grand Cherokee
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Swapping out old plugs for new ones will gain back couple of % of power that was lost from the old plugs wearing out.... ....that is usually what is responsible for any before/after power gain that the aftermarket ignition company suggest....

The camaro in the article looks like it has an aftermarket supercharger.... ....I did say, "mods that has significantly increased the density of the A/F charge in the cylinder or raised top RPM a lot".... ....A supercharger does exactly that to the density of the A/F charge...

If you're so convinced they work, then do it, I'm not convinced... ....just make sure if you do a before/after dyno run, make sure it's legit, use the same plugs as before, or if its a fancy plug claiming to boost power, then use brand new recommended plugs for the "before" dyno run....
 

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JGC
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I had thought about going with the NGK Ruthenium HX vs. the NGK stock Laser Iridium 92145. From everything I read, for our vehicles, the only noticeable difference is the Ruthenium would likely hold up longer. But at 100,000 miles for the stock plugs, I didn't need to spend another $2 a plug when I'm not sure I'll keep it another 100,000 miles. That said, if I had a turbo engine, supercharger, or highly modified/tuned motor, I'd spend the extra $2 per plug. After changing my plugs at 91K, I did notice a slightly smoother engine with what seems to be a slightly quicker throttle response.
 

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I just changed the plugs on my 2012 5.7 Grand Cherokee - 196,371 miles - using Champion 446 plugs from Rock Auto @ $1.31/plug plus shipping. The previous set were also Champion 446 installed at 111,345. With 85,000 on the plugs I was still getting 16-17 city/highway and 19-21 highway. The gap on the removed plugs was approx. 0.050. Attached is a pic of one of the plugs. Given the performance I cannot see the need to use more expensive NGK nickel OEM plugs or platinum or iridium. I definitely do not see the need to replace plugs at the Jeep specified 32K miles. Also, I'm one of the lucky ones replacing my water pump for the first time at 195,000.
228336
 

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Trailhawk
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999 Posts
That plug exhibits an excellent colored insulator nose and wear on the center as well as the ground electrodes. I ran Champion 9055 Iridium spark plugs in my 2011 and they will be going in my 2019. There are numerous offiers with excellent prices on ebay with free shipping.
 

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....I definitely do not see the need to replace plugs at the Jeep specified 32K miles....
I suspect its because the typical life of standard steel plugs is usually ~30k miles in most engines. Most engine also do NOT have dual plugs per cylinder nor have a semi-hemispherical head shape.
You're not the first one to post that their standard steel plug lasted 2-3 times longer than recommended in the HEMI.

The earlier Hemi's used the Champion Plug, they switched to the NGK plug, then switched to NGK Iridium Plugs with a 100k miles change recommendation.
I went with the OEM NGK Iridium Plug recommended for the later HEMI, and have no problem. Keep in mind, NGK makes 2 different Iridium Plugs, get the one that came OEM, not the other.
Judging from the posts, you can use any of the 3 plugs that came OEM with the HEMI over the years and have no problem at all.

Copper plugs just means there is a copper conductor inside the plug, more to keep the tip cool by conducting more heat away from it, the tips are still steel.
Nickle plating is more to prevent the seizing of the plug in the aluminum head, thus you don't need to use anti-seize that might interfere with electrical conduction. I use anti-seize even with Nickle coated plugs and never had a problem.
Platinum plugs typically last 60k miles and it is platinum at the tip where the spark jumps, the harder metal last longer.
Double Platinum plugs typically last 60k miles, they have platinum on the tip and ground, they're for engines with a wasted spark ignition or two plugs per coil schemes, where one plug has reverse current from the spark. If the spark jumps from plain steel to platinum (reversing anode/cathode) the softer metal erodes faster than the hard, that is why for these ignitions the single platinum don't last, you need the double platinum.

Iridium plugs have iridium on the tip. Apparently Iridium doesn't cause faster erosion if you reverse the spark, so there are no double iridium plugs. They typically last 90k-100k miles in most engines.
 

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2014 Summit 5.7 4wd 20" tires swapped to 18", added all skid plates
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I too am surprised at how long plugs last. I usually replace at 50K but based on the conditions of them there is no reason to think they would not have easily made 100K or more. A friend of mine has a Tundra with 300K on it. He bought it at about 100K and has never replaced the plugs. It runs perfectly at idle and WOT. So the plugs in it have at least 200K and possibly 300K. The only thing I can think as to why they sometimes call for these lower mileage replacement intervals is that perhaps during their emission certification they found problems too often if they let the plugs go as long in the test sequence as people are seeing in real life. I see the same thing with PCV valve intervals, I have not had a PCV valve need to be replaced since the 70s, the engines just run too clean to gum them up, yet they still show "check and replace as needed intervals"
 

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I also use anti-seize and had no problem removing the Champion plugs I just changed after 85,000. The plugs were torqued according to spec. 18.5-22 ft-lbs. Mine were done at 20 ft-lbs.
 

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That's the problem with anti-seize, the torque is a dry thread spec, the anti-seize will lube the threads and increase the pressure on the threads for the same amount of torque, you can strip the threads out. I've seen recommendations of reducing torque by as much as 25% if you use anti-seize.

I just follow the instruction on the box for the crush washer, finger tight, then a 3/4 turn, just a regular breaker bar you can tell when the torque goes up quick when you've hit the tight enough point.

Spark plugs don't need to real tight, right on the edge of the spec torque. There are a few engines, only foreign makes come to mind, that plugs have backed out of the head, but never heard of it on a Chrysler engine.
 
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