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Plug erosion


NAXJA Forum User
I have a screaming demon coil in my 96 mail xj and it really seems to be eroding the electrodes pretty fast, would this be a situation where it would be better to upgrade to platinum plugs just for longevity sake? I've had to re gap them twice in 18k miles
Many folks say that copper is best for the 4.0L, but fine wire tips in modern spark plugs are supposed to produce a hotter spark as well as reducing plug erosion with concurrent improved strap materials.

The copper plugs that were in my XJ at the time of purchase were badly worn, and I went straight to Iridium tip. Bosch and Autolite both make an Iridium tip plug. The Autolite has a Pt strap while the Bosch has an Iridium nub on a standard ground strap. I tried both and currently have the Bosch installed. I have a new 0.035" gapped set of Champion Copper Plus on my desk that I'm planning to try some time this week to see if copper really is better.
I have a Screamin Demon plus MSD, I just pulled my plugs out to try some E3 plugs. Not only did the plugs look great but to my surprise I forgot that I was running the NGK equivalent of the Champion Copper truck. I did manage to open the gap to .047" on the NGK's but that's not a option for the E3's so we will see how that works out.
Part of the issue may be that it burns so much oil, this JY motor was full of carbon when I put it in and it consistently uses 1 quart every 300 miles. I'm putting new valve stem seals in it right now because I think that's where it is going, it doesn't leak a drop and doesn't seem to have blowby, the vent tube to air filter is basically dry. Plugs are once again rough so I think I will try some platinum or iridium when I put it back together.
The fuel itself is the most common cause of electrode wear! The vent tube to the air cleaner should be clean as it's the "supply" side, check the manifold for any oil coming from the PCV valve. I had some so I installed a accumulator for that side.