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Old April 16th, 2018, 07:49
tchase tchase is offline
NAXJA Forum User
Join Date: Jul 2004
Location: Nova Scotia, Canada
Posts: 360
Any spark plug gurus?

Ok... So it's time for a tune-up on the old XJ.

Wondering if anyone can offer any advice regarding what plugs to run and/or what the difference is between the 2 different plugs that are spec'd.

I have an '85 with a 2.5L long-block from an '02 Wrangler. Manifolds, fuel, and ignition systems are stock(ish) '85.

The OE plug for the '85 is Champion RFN14LY
The OE plug for the '02 is Champion RC12ECC

Do these 2 plugs physically interchange? My gut says go with the '02 plug as I'm sure it will physically fit but I really don't know much about plugs.
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