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Spark Plug Choices

Black1990jeep

NAXJA Forum User
Location
california
For my 1990 Xj 4.0 liter six, the stock spark plug is a Champion RC9YC But it is not available locally to me, I have been told an AC Delco, Motorcraft, or NKG make suitable plugs for my Jeep.
Which if any is a good alternative to the factory Champion?

I assume a copper plug is fine, or is there a benefit to the fancy platinum plugs, correct?

link to plugs below, This is what I can source tomorrow at OReillys. The Champion I called about and they told me they cant get it, even though it is listed below in the link....

https://www.oreillyauto.com/shop/b/...rk-plug-12874/b14eb31b13d7/1990/jeep/cherokee

Thanks for your spark plug advice!
 
NGK would be my second choice. Use a standard copper core spark plug, platinum plugs can cause issues unless you are using them in the 2000-01 distributor-less engines.

www.rockauto.com has CHAMPION 344 {#RC9YC} and NGK 2460 {#BKR5ES}.
 
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There's something wrong at the store you went to. I've ordered parts that they never carry before, if you have a valid part number for anything they can get it!
 
Sorry but that's nonsense. Try another location or another chain.
 
My 95 calls for Champion 412 (RC12LYC) and NAPA carried them under their house brand name but they were actually manuf by champion (according to the box). On the 4.0 I prefer to use plain ol copper core plugs personally.

Rock Auto lists the Champion 344 for the 90 4.0 (RC9YC) for 1.50 each on their site so obviously they are still available.

https://www.rockauto.com/en/catalog...0l+242cid+l6,1179996,ignition,spark+plug,7212
 
For my 1990 Xj 4.0 liter six, the stock spark plug is a Champion RC9YC But it is not available locally to me, I have been told an AC Delco, Motorcraft, or NKG make suitable plugs for my Jeep.
Which if any is a good alternative to the factory Champion?

I assume a copper plug is fine, or is there a benefit to the fancy platinum plugs, correct?

link to plugs below, This is what I can source tomorrow at OReillys. The Champion I called about and they told me they cant get it, even though it is listed below in the link....

https://www.oreillyauto.com/shop/b/...rk-plug-12874/b14eb31b13d7/1990/jeep/cherokee

Thanks for your spark plug advice!

Champion RC9YC is still available online at a reasonable price- https://www.summitracing.com/parts/cpn-344/year/1990/make/jeep/model/cherokee

Biggest advantage to a platinum plug is longer service life. My rule of thumb for running a platinum plug is to select a similar plug (not counting materials obviously) from the same manufacturer. For example, the factory-specified plug on my '96 XJ 4.0 was a copper Champion RC12LYC. When I changed plugs, I decided to go with a single-platinum Champion RC12PEC5. I figured if those plugs didn't work out, well at least plugs are cheap and easy to change on a 4.0. I ran them for a year, year and a half without issue until the Jeep got totalled.

That being said, Champion lists the platinum plug for your application as being a non-resistor plug, whereas the RC9LYC's have an internal resistor. So for your application, I would just stick with the factory plugs.
 
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